diff --git a/NEWS b/NEWS
index 65852c52..3a4c57c1 100644
--- a/NEWS
+++ b/NEWS
@@ -1,2256 +1,2259 @@
 0.20.24	UNRELEASED
 
  * config: disregard UTF-8 BOM when reading file.
    (Dan Villiom Podlaski Christiansen)
 
  * Skip lines with spaces only in .gitignore. (Andrey Torsunov, #878)
 
  * Add a separate HTTPProxyUnauthorized exception for 407 errors.
    (Jelmer Vernooij, #822)
 
+ * Split out a AbstractHTTPGitClient class.
+   (Jelmer Vernooij)
+
 0.20.23	2021-05-24
 
  * Fix installation of GPG during package publishing.
    (Ruslan Kuprieiev)
 
 0.20.22	2021-05-24
 
  * Prevent removal of refs directory when the last ref is
    deleted. (Jelmer Vernooij)
 
  * Fix filename: MERGE_HEADS => MERGE_HEAD.
    (Jelmer Vernooij, #861)
 
  * For ignored directories, porcelain.add and porcelain.status now only return
    the path to directory itself in the list of ignored paths. Previously, paths
    for all files within the directory would also be included in the list.
    (Peter Rowlands, #853)
 
  * Provide depth argument to ``determine_wants``.
    (Peter Rowlands)
 
  * Various tag signature handling improvements.
    (Daniel Murphy)
 
  * Add separate Tag.verify().  (Peter Rowlands)
 
  * Add support for version 3 index files. (Jelmer Vernooij)
 
  * Fix autocrlf=input handling. (Peter Rowlands, Boris Feld)
 
  * Attempt to find C Git global config on Windows.
    (Peter Rowlands)
 
  API CHANGES
 
  * The APIs for writing and reading individual index entries have changed
    to handle lists of (name, entry) tuples rather than tuples.
 
 0.20.21	2021-03-20
 
  * Add basic support for a GcsObjectStore that stores
    pack files in gcs. (Jelmer Vernooij)
 
  * In porcelain.push, default to local active branch.
    (Jelmer Vernooij, #846)
 
  * Support fetching symrefs.
    (Jelmer Vernooij, #485, #847)
 
  * Add aarch64 wheel building.
    (odidev, Jelmer Vernooij)
 
 0.20.20	2021-03-03
 
  * Implement ``Stash.drop``. (Peter Rowlands)
 
  * Support untracked symlinks to paths outside the
    repository. (Peter Rowlands, #842)
 
 0.20.19	2021-02-11
 
  * Fix handling of negative matches in nested gitignores.
    (Corentin Hembise, #836)
 
 0.20.18	2021-02-04
 
  * Fix formatting in setup.py. (Jelmer Vernooij)
 
  * Add release configuration. (Jelmer Vernooij)
 
 0.20.17	2021-02-04
 
  * credentials: ignore end-of-line character. (Georges Racinet)
 
  * Fix failure in get_untracked_paths when the repository contains symlinks.
    (#830, #793, mattseddon)
 
  * docs: Clarify that Git objects are created on `git add`.
    (Utku Gultopu)
 
 0.20.16	2021-01-16
 
  * Add flag to only attempt to fetch ignored untracked files when specifically requested.
    (Matt Seddon)
 
 0.20.15	2020-12-23
 
  * Add some functions for parsing and writing bundles.
    (Jelmer Vernooij)
 
  * Add ``no_verify`` flag to ``porcelain.commit`` and ``Repo.do_commit``.
    (Peter Rowlands)
 
  * Remove dependency on external mock module.
    (Matěj Cepl, #820)
 
 0.20.14	2020-11-26
 
  * Fix some stash functions on Python 3. (Peter Rowlands)
 
  * Fix handling of relative paths in alternates files on Python 3.
    (Georges Racinet)
 
 0.20.13	2020-11-22
 
  * Add py.typed to allow type checking. (David Caro)
 
  * Add tests demonstrating a bug in the walker code.
    (Doug Hellman)
 
 0.20.11	2020-10-30
 
  * Fix wheels build on Linux. (Ruslan Kuprieiev)
 
  * Enable wheels build for Python 3.9 on Linux. (Jelmer Vernooij)
 
 0.20.8	2020-10-29
 
  * Build wheels on Mac OS X / Windows for Python 3.9.
    (Jelmer Vernooij)
 
 0.20.7	2020-10-29
 
  * Check core.repositoryformatversion. (Jelmer Vernooij, #803)
 
  * Fix ACK/NACK handling in archive command handling in dulwich.client.
    (DzmitrySudnik, #805)
 
 0.20.6	2020-08-29
 
  * Add a ``RefsContainer.watch`` interface.
    (Jelmer Vernooij, #751)
 
  * Fix pushing of new branches from porcelain.push.
    (Jelmer Vernooij, #788)
 
  * Honor shallows when pushing from a shallow clone.
    (Jelmer Vernooij, #794)
 
  * Fix porcelain.path_to_tree_path for Python 3.5.
    (Boris Feld, #777)
 
  * Add support for honor proxy environment variables for HTTP.
    (Aurélien Campéas, #797)
 
 0.20.5	2020-06-22
 
  * Print a clearer exception when setup.py is executed on Python < 3.5.
    (Jelmer Vernooij, #783)
 
  * Send an empty pack to clients if they requested objects, even if they
    already have those objects. Thanks to Martijn Pieters for
    the detailed bug report. (Jelmer Vernooij, #781)
 
  * porcelain.pull: Don't ask for objects that we already have.
    (Jelmer Vernooij, #782)
 
  * Add LCA implementation. (Kevin Hendricks)
 
  * Add functionality for finding the merge base. (Kevin Hendricks)
 
  * Check for diverged branches during push.
    (Jelmer Vernooij, #494)
 
  * Check for fast-forward during pull. (Jelmer Vernooij, #666)
 
  * Return a SendPackResult object from
    GitClient.send_pack(). (Jelmer Vernooij)
 
  * ``GitClient.send_pack`` now sets the ``ref_status`` attribute
    on its return value to a dictionary mapping ref names
    to error messages. Previously, it raised UpdateRefsError
    if any of the refs failed to update.
    (Jelmer Vernooij, #780)
 
  * Add a ``porcelain.Error`` object that most errors in porcelain
    derive from. (Jelmer Vernooij)
 
  * Fix argument parsing in dulwich command-line app.
    (Jelmer Vernooij, #784)
 
 0.20.3	2020-06-14
 
  * Add support for remembering remote refs after push/pull.
    (Jelmer Vernooij, #752)
 
  * Support passing tree and output encoding to
    dulwich.patch.unified_diff. (Jelmer Vernooij, #763)
 
  * Fix pushing of new refs over HTTP(S) when there are
    no new objects to be sent.
    (Jelmer Vernooij, #739)
 
  * Raise new error HTTPUnauthorized when the server sends
    back a 401. The client can then retry with credentials.
    (Jelmer Vernooij, #691)
 
  * Move the guts of bin/dulwich to dulwich.cli, so it is easier to
    test or import. (Jelmer Vernooij)
 
  * Install dulwich script from entry_points when setuptools is available,
    making it slightly easier to use on Windows. (Jelmer Vernooij, #540)
 
  * Set python_requires>=3.5 in setup.py. (Manuel Jacob)
 
 0.20.2	2020-06-01
 
  * Brown bag release to fix uploads of Windows wheels.
 
 0.20.1	2020-06-01
 
  * Publish binary wheels for: Windows, Linux, Mac OS X.
    (Jelmer Vernooij, #711, #710, #629)
 
 0.20.0	2020-06-01
 
  * Drop support for Python 2. (Jelmer Vernooij)
 
  * Only return files from the loose store that look like git objects.
    (Nicolas Dandrimont)
 
  * Ignore agent= capability if sent by client.
    (Jelmer Vernooij)
 
  * Don't break when encountering block devices.
    (Jelmer Vernooij)
 
  * Decode URL paths in HttpGitClient using utf-8 rather than file system
    encoding. (Manuel Jacob)
 
  * Fix pushing from a shallow clone.
    (Brecht Machiels, #705)
 
 0.19.16	2020-04-17
 
  * Don't send "deepen None" to server if graph walker
    supports shallow. (Jelmer Vernooij, #747)
 
  * Support tweaking the compression level for
    loose objects through the "core.looseCompression" and
    "core.compression" settings. (Jelmer Vernooij)
 
  * Support tweaking the compression level for
    pack objects through the "core.packCompression" and
    "core.compression" settings. (Jelmer Vernooij)
 
  * Add a "dulwich.contrib.diffstat" module.
    (Kevin Hendricks)
 
 0.19.15	2020-01-26
 
  * Properly handle files that are just executable for the
    current user. (Jelmer Vernooij, #734)
 
  * Fix handling of stored encoding in
    ``dulwich.porcelain.get_object_by_path`` on Python 3.
    (Jelmer Vernooij)
 
  * Support the include_trees and rename_detector arguments
    at the same time when diffing trees.
    (Jelmer Vernooij)
 
 0.19.14	2019-11-30
 
  * Strip superfluous <> around email. (monnerat)
 
  * Stop checking for ref validity client-side. Users can
    still call check_wants manually. (Jelmer Vernooij)
 
  * Switch over to Google-style docstrings.
    (Jelmer Vernooij)
 
  * Add a ``dulwich.porcelain.active_branch`` function.
    (Jelmer Vernooij)
 
  * Cleanup new directory if clone fails. (Jelmer Vernooij, #733)
 
  * Expand "~" in global exclude path. (Jelmer Vernooij)
 
 0.19.13	2019-08-19
 
  BUG FIXES
 
  * Avoid ``PermissionError``, since it is Python3-specific.
    (Jelmer Vernooij)
 
  * Fix regression that added a dependency on C git for the
    test suite. (Jelmer Vernooij, #720)
 
  * Fix compatibility with Python 3.8 - mostly deprecation warnings.
    (Jelmer Vernooij)
 
 0.19.12	2019-08-13
 
  BUG FIXES
 
  * Update directory detection for `get_unstaged_changes` for Python 3.
    (Boris Feld, #684)
 
  * Add a basic ``porcelain.clean``. (Lane Barlow, #398)
 
  * Fix output format of ``porcelain.diff`` to match that of
    C Git. (Boris Feld)
 
  * Return a 404 not found error when repository is not found.
 
  * Mark ``.git`` directories as hidden on Windows.
    (Martin Packman, #585)
 
  * Implement ``RefsContainer.__iter__``
    (Jelmer Vernooij, #717)
 
  * Don't trust modes if they can't be modified after a file has been created.
    (Jelmer Vernooij, #719)
 
 0.19.11	2019-02-07
 
  IMPROVEMENTS
 
  * Use fullname from gecos field, if available.
    (Jelmer Vernooij)
 
  * Support ``GIT_AUTHOR_NAME`` / ``GIT_AUTHOR_EMAIL``.
    (Jelmer Vernooij)
 
  * Add support for short ids in parse_commit. (Jelmer Vernooij)
 
  * Add support for ``prune`` and ``prune_tags`` arguments
    to ``porcelain.fetch``. (Jelmer Vernooij, #681)
 
  BUG FIXES
 
   * Fix handling of race conditions when new packs appear.
     (Jelmer Vernooij)
 
 0.19.10	2018-01-15
 
  IMPROVEMENTS
 
  * Add `dulwich.porcelain.write_tree`.
    (Jelmer Vernooij)
 
  * Support reading ``MERGE_HEADS`` in ``Repo.do_commit``.
    (Jelmer Vernooij)
 
  * Import from ``collections.abc`` rather than ``collections`` where
    applicable. Required for 3.8 compatibility.
    (Jelmer Vernooij)
 
  * Support plain strings as refspec arguments to
    ``dulwich.porcelain.push``. (Jelmer Vernooij)
 
  * Add support for creating signed tags.
    (Jelmer Vernooij, #542)
 
  BUG FIXES
 
  *  Handle invalid ref that pretends to be a sub-folder under a valid ref.
     (KS Chan)
 
 0.19.9	2018-11-17
 
  BUG FIXES
 
  * Avoid fetching ghosts in ``Repo.fetch``.
    (Jelmer Vernooij)
 
  * Preserve port and username in parsed HTTP URLs.
    (Jelmer Vernooij)
 
  * Add basic server side implementation of ``git-upload-archive``.
    (Jelmer Vernooij)
 
 0.19.8	2018-11-06
 
  * Fix encoding when reading README file in setup.py.
    (egor <egor@sourced.tech>, #668)
 
 0.19.7	2018-11-05
 
  CHANGES
 
   * Drop support for Python 3 < 3.4. This is because
     pkg_resources (which get used by setuptools and mock)
     no longer supports 3.3 and earlier. (Jelmer Vernooij)
 
  IMPROVEMENTS
 
   * Support ``depth`` argument to ``GitClient.fetch_pack`` and support
     fetching and updating shallow metadata. (Jelmer Vernooij, #240)
 
  BUG FIXES
 
   * Don't write to stdout and stderr when they are not available
     (such as is the case for pythonw). (Sylvia van Os, #652)
 
   * Fix compatibility with newer versions of git, which expect CONTENT_LENGTH
     to be set to 0 for empty body requests. (Jelmer Vernooij, #657)
 
   * Raise an exception client-side when a caller tries to request
     SHAs that are not directly referenced the servers' refs.
     (Jelmer Vernooij)
 
   * Raise more informative errors when unable to connect to repository
     over SSH or subprocess. (Jelmer Vernooij)
 
   * Handle commit identity fields with multiple ">" characters.
     (Nicolas Dandrimont)
 
  IMPROVEMENTS
 
   * ``dulwich.porcelain.get_object_by_path`` method for easily
     accessing a path in another tree. (Jelmer Vernooij)
 
   * Support the ``i18n.commitEncoding`` setting in config.
     (Jelmer Vernooij)
 
 0.19.6	2018-08-11
 
  BUG FIXES
 
   * Fix support for custom transport arguments in ``dulwich.porcelain.clone``.
     (Semyon Slepov)
 
   * Fix compatibility with Python 3.8 (Jelmer Vernooij, Daniel M. Capella)
 
   * Fix some corner cases in ``path_to_tree_path``. (Romain Keramitas)
 
   * Support paths as bytestrings in various places in ``dulwich.index``
     (Jelmer Vernooij)
 
   * Avoid setup.cfg for now, since it seems to break pypi metadata.
     (Jelmer Vernooij, #658)
 
 0.19.5	2018-07-08
 
  IMPROVEMENTS
 
   * Add ``porcelain.describe``. (Sylvia van Os)
 
  BUG FIXES
 
   * Fix regression in ``dulwich.porcelain.clone`` that prevented cloning
     of remote repositories. (Jelmer Vernooij, #639)
 
   * Don't leave around empty parent directories for removed refs.
     (Damien Tournoud, #640)
 
 0.19.4	2018-06-24
 
  IMPROVEMENTS
 
   * Add ``porcelain.ls_files``. (Jelmer Vernooij)
 
   * Add ``Index.items``. (Jelmer Vernooij)
 
  BUG FIXES
 
   * Avoid unicode characters (e.g. the digraph ij in my surname) in setup.cfg,
     since setuptools doesn't deal well with them. See
     https://github.com/pypa/setuptools/issues/1062. (Jelmer Vernooij, #637)
 
 0.19.3	2018-06-17
 
  IMPROVEMENTS
 
   * Add really basic `dulwich.porcelain.fsck` implementation.
     (Jelmer Vernooij)
 
   * When the `DULWICH_PDB` environment variable is set, make
     SIGQUIT open pdb in the 'dulwich' command.
 
   * Add `checkout` argument to `Repo.clone`.
     (Jelmer Vernooij, #503)
 
   * Add `Repo.get_shallow` method. (Jelmer Vernooij)
 
   * Add basic `dulwich.stash` module. (Jelmer Vernooij)
 
   * Support a `prefix` argument to `dulwich.archive.tar_stream`.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Fix handling of encoding for tags. (Jelmer Vernooij, #608)
 
   * Fix tutorial tests on Python 3. (Jelmer Vernooij, #573)
 
   * Fix remote refs created by `porcelain.fetch`. (Daniel Andersson, #623)
 
   * More robust pack creation on Windows. (Daniel Andersson)
 
   * Fix recursive option for `porcelain.ls_tree`. (Romain Keramitas)
 
  TESTS
 
   * Some improvements to paramiko tests. (Filipp Frizzy)
 
 0.19.2	2018-04-07
 
  BUG FIXES
 
   * Fix deprecated Index.iterblobs method.
     (Jelmer Vernooij)
 
 0.19.1	2018-04-05
 
  IMPROVEMENTS
 
   * Add 'dulwich.mailmap' file for reading mailmap files.
     (Jelmer Vernooij)
 
   * Dulwich no longer depends on urllib3[secure]. Instead,
     "dulwich[https]" can be used to pull in the necessary
     dependencies for HTTPS support. (Jelmer Vernooij, #616)
 
   * Support the `http.sslVerify` and `http.sslCAInfo`
     configuration options. (Jelmer Vernooij)
 
   * Factor out `dulwich.client.parse_rsync_url` function.
     (Jelmer Vernooij)
 
   * Fix repeat HTTP requests using the same smart HTTP client.
     (Jelmer Vernooij)
 
   * New 'client.PLinkSSHVendor' for creating connections using PuTTY's plink.exe.
     (Adam Bradley, Filipp Frizzy)
 
   * Only pass in `key_filename` and `password` to SSHVendor
     implementations if those parameters are set.
     (This helps with older SSHVendor implementations)
     (Jelmer Vernooij)
 
  API CHANGES
 
   * Index.iterblobs has been renamed to Index.iterobjects.
     (Jelmer Vernooij)
 
 0.19.0	2018-03-10
 
  BUG FIXES
 
   * Make `dulwich.archive` set the gzip header file modification time so that
     archives created from the same Git tree are always identical.
     (#577, Jonas Haag)
 
   * Allow comment characters (#, ;) within configuration file strings
     (Daniel Andersson, #579)
 
   * Raise exception when passing in invalid author/committer values
     to Repo.do_commit(). (Jelmer Vernooij, #602)
 
  IMPROVEMENTS
 
   * Add a fastimport ``extra``. (Jelmer Vernooij)
 
   * Start writing reflog entries. (Jelmer Vernooij)
 
   * Add ability to use password and keyfile ssh options with SSHVendor. (Filipp Kucheryavy)
 
   * Add ``change_type_same`` flag to ``tree_changes``.
     (Jelmer Vernooij)
 
  API CHANGES
 
   * ``GitClient.send_pack`` now accepts a ``generate_pack_data``
     rather than a ``generate_pack_contents`` function for
     performance reasons. (Jelmer Vernooij)
 
   * Dulwich now uses urllib3 internally for HTTP requests.
     The `opener` argument to `dulwich.client.HttpGitClient` that took a
     `urllib2` opener instance has been replaced by a `pool_manager` argument
     that takes a `urllib3` pool manager instance.
     (Daniel Andersson)
 
 0.18.6	2017-11-11
 
  BUG FIXES
 
   * Fix handling of empty repositories in ``porcelain.clone``.
     (#570, Jelmer Vernooij)
 
   * Raise an error when attempting to add paths that are not under the
     repository. (Jelmer Vernooij)
 
   * Fix error message for missing trailing ]. (Daniel Andersson)
 
   * Raise EmptyFileException when corruption (in the form of an empty
     file) is detected. (Antoine R. Dumont, #582)
 
   IMPROVEMENTS
 
   * Enforce date field parsing consistency. This also add checks on
     those date fields for potential overflow.
     (Antoine R. Dumont, #567)
 
 0.18.5	2017-10-29
 
  BUG FIXES
 
   * Fix cwd for hooks. (Fabian Grünbichler)
 
   * Fix setting of origin in config when non-standard origin is passed into
     ``Repo.clone``. (Kenneth Lareau, #565)
 
   * Prevent setting SSH arguments from SSH URLs when using SSH through a
     subprocess. Note that Dulwich doesn't support cloning submodules.
     (CVE-2017-16228) (Jelmer Vernooij)
 
  IMPROVEMENTS
 
   * Silently ignored directories in ``Repo.stage``.
     (Jelmer Vernooij, #564)
 
  API CHANGES
 
   * GitFile now raises ``FileLocked`` when encountering a lock
     rather than OSError(EEXIST). (Jelmer Vernooij)
 
 0.18.4	2017-10-01
 
  BUG FIXES
 
   * Make default User-Agent start with "git/" because GitHub won't response to
     HTTP smart server requests otherwise (and reply with a 404).
     (Jelmer vernooij, #562)
 
 0.18.3	2017-09-03
 
  BUG FIXES
 
   * Read config during porcelain operations that involve remotes.
     (Jelmer Vernooij, #545)
 
   * Fix headers of empty chunks in unified diffs. (Taras Postument, #543)
 
   * Properly follow redirects over HTTP. (Jelmer Vernooij, #117)
 
  IMPROVEMENTS
 
   * Add ``dulwich.porcelain.update_head``. (Jelmer Vernooij, #439)
 
   * ``GitClient.fetch_pack`` now returns symrefs.
     (Jelmer Vernooij, #485)
 
   * The server now supports providing symrefs.
     (Jelmer Vernooij, #485)
 
   * Add ``dulwich.object_store.commit_tree_changes`` to incrementally
     commit changes to a tree structure. (Jelmer Vernooij)
 
   * Add basic ``PackBasedObjectStore.repack`` method.
     (Jelmer Vernooij, Earl Chew, #296, #549, #552)
 
 0.18.2	2017-08-01
 
  TEST FIXES
 
   * Use constant timestamp so tests pass in all timezones, not just BST.
     (Jelmer Vernooij)
 
 0.18.1	2017-07-31
 
  BUG FIXES
 
   * Fix syntax error in dulwich.contrib.test_swift_smoke.
     (Jelmer Vernooij)
 
 0.18.0	2017-07-31
 
  BUG FIXES
 
   * Fix remaining tests on Windows. (Jelmer Vernooij, #493)
 
   * Fix build of C extensions with Python 3 on Windows.
     (Jelmer Vernooij)
 
   * Pass 'mkdir' argument onto Repo.init_bare in Repo.clone.
     (Jelmer Vernooij, #504)
 
   * In ``dulwich.porcelain.add``, if no files are specified,
     add from current working directory rather than repository root.
     (Jelmer Vernooij, #521)
 
   * Properly deal with submodules in 'porcelain.status'.
     (Jelmer Vernooij, #517)
 
   * ``dulwich.porcelain.remove`` now actually removes files from
     disk, not just from the index. (Jelmer Vernooij, #488)
 
   * Fix handling of "reset" command with markers and without
     "from". (Antoine Pietri)
 
   * Fix handling of "merge" command with markers. (Antoine Pietri)
 
   * Support treeish argument to porcelain.reset(), rather than
     requiring a ref/commit id. (Jelmer Vernooij)
 
   * Handle race condition when mtime doesn't change between writes/reads.
     (Jelmer Vernooij, #541)
 
   * Fix ``dulwich.porcelain.show`` on commits with Python 3.
     (Jelmer Vernooij, #532)
 
  IMPROVEMENTS
 
   * Add basic support for reading ignore files in ``dulwich.ignore``.
     ``dulwich.porcelain.add`` and ``dulwich.porcelain.status`` now honor
     ignores. (Jelmer Vernooij, Segev Finer, #524, #526)
 
   * New ``dulwich.porcelain.check_ignore`` command.
     (Jelmer Vernooij)
 
   * ``dulwich.porcelain.status`` now supports a ``ignored`` argument.
     (Jelmer Vernooij)
 
  DOCUMENTATION
 
   * Clarified docstrings for Client.{send_pack,fetch_pack} implementations.
     (Jelmer Vernooij, #523)
 
 0.17.3	2017-03-20
 
  PLATFORM SUPPORT
 
   * List Python 3.3 as supported. (Jelmer Vernooij, #513)
 
  BUG FIXES
 
   * Fix compatibility with pypy 3. (Jelmer Vernooij)
 
 0.17.2	2017-03-19
 
  BUG FIXES
 
   * Add workaround for
     https://bitbucket.org/pypy/pypy/issues/2499/cpyext-pystring_asstring-doesnt-work,
     fixing Dulwich when used with C extensions on pypy < 5.6. (Victor Stinner)
 
   * Properly quote config values with a '#' character in them.
     (Jelmer Vernooij, #511)
 
 0.17.1	2017-03-01
 
  IMPROVEMENTS
 
   * Add basic 'dulwich pull' command. (Jelmer Vernooij)
 
  BUG FIXES
 
   * Cope with existing submodules during pull.
     (Jelmer Vernooij, #505)
 
 0.17.0	2017-03-01
 
  TEST FIXES
 
   * Skip test that requires sync to synchronize filesystems if os.sync is
     not available. (Koen Martens)
 
  IMPROVEMENTS
 
   * Implement MemoryRepo.{set_description,get_description}.
     (Jelmer Vernooij)
 
   * Raise exception in Repo.stage() when absolute paths are
     passed in. Allow passing in relative paths to
     porcelain.add().(Jelmer Vernooij)
 
  BUG FIXES
 
   * Handle multi-line quoted values in config files.
     (Jelmer Vernooij, #495)
 
   * Allow porcelain.clone of repository without HEAD.
     (Jelmer Vernooij, #501)
 
   * Support passing tag ids to Walker()'s include argument.
     (Jelmer Vernooij)
 
   * Don't strip trailing newlines from extra headers.
     (Nicolas Dandrimont)
 
   * Set bufsize=0 for subprocess interaction with SSH client.
     Fixes hangs on Python 3. (René Stern, #434)
 
   * Don't drop first slash for SSH paths, except for those
     starting with "~". (Jelmer Vernooij, René Stern, #463)
 
   * Properly log off after retrieving just refs.
     (Jelmer Vernooij)
 
 0.16.3	2016-01-14
 
  TEST FIXES
 
   * Remove racy check that relies on clock time changing between writes.
     (Jelmer Vernooij)
 
  IMPROVEMENTS
 
   * Add porcelain.remote_add. (Jelmer Vernooij)
 
 0.16.2	2016-01-14
 
  IMPROVEMENTS
 
   * Fixed failing test-cases on windows.
     (Koen Martens)
 
  API CHANGES
 
   * Repo is now a context manager, so that it can be easily
     closed using a ``with`` statement. (Søren Løvborg)
 
  TEST FIXES
 
   * Only run worktree list compat tests against git 2.7.0,
     when 'git worktree list' was introduced. (Jelmer Vernooij)
 
  BUG FIXES
 
   * Ignore filemode when building index when core.filemode
     is false.
     (Koen Martens)
 
   * Initialize core.filemode configuration setting by
     probing the filesystem for trustable permissions.
     (Koen Martens)
 
   * Fix ``porcelain.reset`` to respect the comittish argument.
     (Koen Martens)
 
   * Fix dulwich.porcelain.ls_remote() on Python 3.
     (#471, Jelmer Vernooij)
 
   * Allow both unicode and byte strings for host paths
     in dulwich.client. (#435, Jelmer Vernooij)
 
   * Add remote from porcelain.clone. (#466, Jelmer Vernooij)
 
   * Fix unquoting of credentials before passing to urllib2.
     (#475, Volodymyr Holovko)
 
   * Cope with submodules in `build_index_from_tree`.
     (#477, Jelmer Vernooij)
 
   * Handle deleted files in `get_unstaged_changes`.
     (#483, Doug Hellmann)
 
   * Don't overwrite files when they haven't changed in
     `build_file_from_blob`.
     (#479, Benoît HERVIER)
 
   * Check for existence of index file before opening pack.
     Fixes a race when new packs are being added.
     (#482, wme)
 
 0.16.1	2016-12-25
 
  BUG FIXES
 
   * Fix python3 compatibility for dulwich.contrib.release_robot.
     (Jelmer Vernooij)
 
 0.16.0	2016-12-24
 
  IMPROVEMENTS
 
   * Add support for worktrees. See `git-worktree(1)` and
     `gitrepository-layout(5)`. (Laurent Rineau)
 
   * Add support for `commondir` file in Git control
     directories. (Laurent Rineau)
 
   * Add support for passwords in HTTP URLs.
     (Jon Bain, Mika Mäenpää)
 
   * Add `release_robot` script to contrib,
     allowing easy finding of current version based on Git tags.
     (Mark Mikofski)
 
   * Add ``Blob.splitlines`` method.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Fix handling of ``Commit.tree`` being set to an actual
     tree object rather than a tree id. (Jelmer Vernooij)
 
   * Return remote refs from LocalGitClient.fetch_pack(),
     consistent with the documentation for that method.
     (#461, Jelmer Vernooij)
 
   * Fix handling of unknown URL schemes in get_transport_and_path.
     (#465, Jelmer Vernooij)
 
 0.15.0	2016-10-09
 
  BUG FIXES
 
   * Allow missing trailing LF when reading service name from
     HTTP servers. (Jelmer Vernooij, Andrew Shadura, #442)
 
   * Fix dulwich.porcelain.pull() on Python3. (Jelmer Vernooij, #451)
 
   * Properly pull in tags during dulwich.porcelain.clone.
     (Jelmer Vernooij, #408)
 
  CHANGES
 
   * Changed license from "GNU General Public License, version 2.0 or later"
     to "Apache License, version 2.0 or later or GNU General Public License,
     version 2.0 or later". (#153)
 
  IMPROVEMENTS
 
   * Add ``dulwich.porcelain.ls_tree`` implementation. (Jelmer Vernooij)
 
 0.14.1	2016-07-05
 
  BUG FIXES
 
   * Fix regression removing untouched refs when pushing over SSH.
     (Jelmer Vernooij #441)
 
   * Skip Python3 tests for SWIFT contrib module, as it has not yet
     been ported.
 
 0.14.0	2016-07-03
 
  BUG FIXES
 
   * Fix ShaFile.id after modification of a copied ShaFile.
     (Félix Mattrat, Jelmer Vernooij)
 
   * Support removing refs from porcelain.push.
     (Jelmer Vernooij, #437)
 
   * Stop magic protocol ref `capabilities^{}` from leaking out
     to clients. (Jelmer Vernooij, #254)
 
  IMPROVEMENTS
 
   * Add `dulwich.config.parse_submodules` function.
 
   * Add `RefsContainer.follow` method. (#438)
 
 0.13.0	2016-04-24
 
  IMPROVEMENTS
 
   * Support `ssh://` URLs in get_transport_and_path_from_url().
     (Jelmer Vernooij, #402)
 
   * Support missing empty line after headers in Git commits and tags.
     (Nicolas Dandrimont, #413)
 
   * Fix `dulwich.porcelain.status` when used in empty trees.
     (Jelmer Vernooij, #415)
 
   * Return copies of objects in MemoryObjectStore rather than
     references, making the behaviour more consistent with that of
     DiskObjectStore. (Félix Mattrat, Jelmer Vernooij)
 
   * Fix ``dulwich.web`` on Python3. (#295, Jonas Haag)
 
  CHANGES
 
   * Drop support for Python 2.6.
 
   * Fix python3 client web support. (Jelmer Vernooij)
 
  BUG FIXES
 
   * Fix hang on Gzip decompression. (Jonas Haag)
 
   * Don't rely on working tell() and seek() methods
     on wsgi.input. (Jonas Haag)
 
   * Support fastexport/fastimport functionality on python3 with newer
     versions of fastimport (>= 0.9.5). (Jelmer Vernooij, Félix Mattrat)
 
 0.12.0	2015-12-13
 
  IMPROVEMENTS
 
   * Add a `dulwich.archive` module that can create tarballs.
     Based on code from Jonas Haag in klaus.
 
   * Add a `dulwich.reflog` module for reading and writing reflogs.
     (Jelmer Vernooij)
 
   * Fix handling of ambiguous refs in `parse_ref` to make
     it match the behaviour described in https://git-scm.com/docs/gitrevisions.
     (Chris Bunney)
 
   * Support Python3 in C modules. (Lele Gaifax)
 
  BUG FIXES
 
   * Simplify handling of SSH command invocation.
     Fixes quoting of paths. Thanks, Thomas Liebetraut. (#384)
 
   * Fix inconsistent handling of trailing slashes for DictRefsContainer. (#383)
 
   * Add hack to support thin packs duing fetch(), albeit while requiring the
     entire pack file to be loaded into memory. (jsbain)
 
  CHANGES
 
   * This will be the last release to support Python 2.6.
 
 0.11.2	2015-09-18
 
  IMPROVEMENTS
 
   * Add support for agent= capability. (Jelmer Vernooij, #298)
 
   * Add support for quiet capability. (Jelmer Vernooij)
 
  CHANGES
 
   * The ParamikoSSHVendor class has been moved to
   * dulwich.contrib.paramiko_vendor, as it's currently untested.
     (Jelmer Vernooij, #364)
 
 0.11.1	2015-09-13
 
  Fix-up release to exclude broken blame.py file.
 
 0.11.0	2015-09-13
 
  IMPROVEMENTS
 
   * Extended Python3 support to most of the codebase.
     (Gary van der Merwe, Jelmer Vernooij)
   * The `Repo` object has a new `close` method that can be called to close any
     open resources. (Gary van der Merwe)
   * Support 'git.bat' in SubprocessGitClient on Windows.
     (Stefan Zimmermann)
   * Advertise 'ofs-delta' capability in receive-pack server side
     capabilities. (Jelmer Vernooij)
   * Switched `default_local_git_client_cls` to `LocalGitClient`.
     (Gary van der Merwe)
   * Add `porcelain.ls_remote` and `GitClient.get_refs`.
     (Michael Edgar)
   * Add `Repo.discover` method. (B. M. Corser)
   * Add `dulwich.objectspec.parse_refspec`. (Jelmer Vernooij)
   * Add `porcelain.pack_objects` and `porcelain.repack`.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Fix handling of 'done' in graph walker and implement the
     'no-done' capability. (Tommy Yu, #88)
 
   * Avoid recursion limit issues resolving deltas. (William Grant, #81)
 
   * Allow arguments in local client binary path overrides.
     (Jelmer Vernooij)
 
   * Fix handling of commands with arguments in paramiko SSH
     client. (Andreas Klöckner, Jelmer Vernooij, #363)
 
   * Fix parsing of quoted strings in configs. (Jelmer Vernooij, #305)
 
 0.10.1  2015-03-25
 
  BUG FIXES
 
   * Return `ApplyDeltaError` when encountering delta errors
     in both C extensions and native delta application code.
     (Jelmer Vernooij, #259)
 
 0.10.0	2015-03-22
 
  BUG FIXES
 
   * In dulwich.index.build_index_from_tree, by default
     refuse to create entries that start with .git/.
     (Jelmer Vernooij, CVE-2014-9706)
 
   * Fix running of testsuite when installed.
     (Jelmer Vernooij, #223)
 
   * Use a block cache in _find_content_rename_candidates(),
     improving performance. (Mike Williams)
 
   * Add support for ``core.protectNTFS`` setting.
     (Jelmer Vernooij)
 
   * Fix TypeError when fetching empty updates.
     (Hwee Miin Koh)
 
   * Resolve delta refs when pulling into a MemoryRepo.
     (Max Shawabkeh, #256)
 
   * Fix handling of tags of non-commits in missing object finder.
     (Augie Fackler, #211)
 
   * Explicitly disable mmap on plan9 where it doesn't work.
     (Jeff Sickel)
 
  IMPROVEMENTS
 
   * New public method `Repo.reset_index`. (Jelmer Vernooij)
 
   * Prevent duplicate parsing of loose files in objects
     directory when reading. Thanks to David Keijser for the
     report. (Jelmer Vernooij, #231)
 
 0.9.9	2015-03-20
 
  SECURITY BUG FIXES
 
   * Fix buffer overflow in C implementation of pack apply_delta().
     (CVE-2015-0838)
 
     Thanks to Ivan Fratric of the Google Security Team for
     reporting this issue.
     (Jelmer Vernooij)
 
 0.9.8	2014-11-30
 
  BUG FIXES
 
   * Various fixes to improve test suite running on Windows.
     (Gary van der Merwe)
 
   * Limit delta copy length to 64K in v2 pack files. (Robert Brown)
 
   * Strip newline from final ACKed SHA while fetching packs.
     (Michael Edgar)
 
   * Remove assignment to PyList_SIZE() that was causing segfaults on
     pypy. (Jelmer Vernooij, #196)
 
  IMPROVEMENTS
 
   * Add porcelain 'receive-pack' and 'upload-pack'. (Jelmer Vernooij)
 
   * Handle SIGINT signals in bin/dulwich. (Jelmer Vernooij)
 
   * Add 'status' support to bin/dulwich. (Jelmer Vernooij)
 
   * Add 'branch_create', 'branch_list', 'branch_delete' porcelain.
     (Jelmer Vernooij)
 
   * Add 'fetch' porcelain. (Jelmer Vernooij)
 
   * Add 'tag_delete' porcelain. (Jelmer Vernooij)
 
   * Add support for serializing/deserializing 'gpgsig' attributes in Commit.
     (Jelmer Vernooij)
 
  CHANGES
 
   * dul-web is now available as 'dulwich web-daemon'.
     (Jelmer Vernooij)
 
   * dulwich.porcelain.tag has been renamed to tag_create.
     dulwich.porcelain.list_tags has been renamed to tag_list.
     (Jelmer Vernooij)
 
  API CHANGES
 
   * Restore support for Python 2.6. (Jelmer Vernooij, Gary van der Merwe)
 
 
 0.9.7	2014-06-08
 
  BUG FIXES
 
   * Fix tests dependent on hash ordering. (Michael Edgar)
 
   * Support staging symbolic links in Repo.stage.
     (Robert Brown)
 
   * Ensure that all files object are closed when running the test suite.
     (Gary van der Merwe)
 
   * When writing OFS_DELTA pack entries, write correct offset.
     (Augie Fackler)
 
   * Fix handler of larger copy operations in packs. (Augie Fackler)
 
   * Various fixes to improve test suite running on Windows.
     (Gary van der Merwe)
 
   * Fix logic for extra adds of identical files in rename detector.
     (Robert Brown)
 
  IMPROVEMENTS
 
   * Add porcelain 'status'. (Ryan Faulkner)
 
   * Add porcelain 'daemon'. (Jelmer Vernooij)
 
   * Add `dulwich.greenthreads` module which provides support
     for concurrency of some object store operations.
     (Fabien Boucher)
 
   * Various changes to improve compatibility with Python 3.
     (Gary van der Merwe, Hannu Valtonen, michael-k)
 
   * Add OpenStack Swift backed repository implementation
     in dulwich.contrib. See README.swift for details. (Fabien Boucher)
 
 API CHANGES
 
   * An optional close function can be passed to the Protocol class. This will
     be called by its close method. (Gary van der Merwe)
 
   * All classes with close methods are now context managers, so that they can
     be easily closed using a `with` statement. (Gary van der Merwe)
 
   * Remove deprecated `num_objects` argument to `write_pack` methods.
     (Jelmer Vernooij)
 
  OTHER CHANGES
 
   * The 'dul-daemon' script has been removed. The same functionality
     is now available as 'dulwich daemon'. (Jelmer Vernooij)
 
 0.9.6	2014-04-23
 
  IMPROVEMENTS
 
   * Add support for recursive add in 'git add'.
     (Ryan Faulkner, Jelmer Vernooij)
 
   * Add porcelain 'list_tags'. (Ryan Faulkner)
 
   * Add porcelain 'push'. (Ryan Faulkner)
 
   * Add porcelain 'pull'. (Ryan Faulkner)
 
   * Support 'http.proxy' in HttpGitClient.
     (Jelmer Vernooij, #1096030)
 
   * Support 'http.useragent' in HttpGitClient.
     (Jelmer Vernooij)
 
   * In server, wait for clients to send empty list of
     wants when talking to empty repository.
     (Damien Tournoud)
 
   * Various changes to improve compatibility with
     Python 3. (Gary van der Merwe)
 
  BUG FIXES
 
   * Support unseekable 'wsgi.input' streams.
     (Jonas Haag)
 
   * Raise TypeError when passing unicode() object
     to Repo.__getitem__.
     (Jonas Haag)
 
   * Fix handling of `reset` command in dulwich.fastexport.
     (Jelmer Vernooij, #1249029)
 
   * In client, don't wait for server to close connection
     first. Fixes hang when used against GitHub
     server implementation. (Siddharth Agarwal)
 
   * DeltaChainIterator: fix a corner case where an object is inflated as an
     object already in the repository.
     (Damien Tournoud, #135)
 
   * Stop leaking file handles during pack reload. (Damien Tournoud)
 
   * Avoid reopening packs during pack cache reload. (Jelmer Vernooij)
 
  API CHANGES
 
   * Drop support for Python 2.6. (Jelmer Vernooij)
 
 0.9.5	2014-02-23
 
  IMPROVEMENTS
 
   * Add porcelain 'tag'. (Ryan Faulkner)
 
   * New module `dulwich.objectspec` for parsing strings referencing
     objects and commit ranges. (Jelmer Vernooij)
 
   * Add shallow branch support. (milki)
 
   * Allow passing urllib2 `opener` into HttpGitClient.
     (Dov Feldstern, #909037)
 
  CHANGES
 
   * Drop support for Python 2.4 and 2.5. (Jelmer Vernooij)
 
  API CHANGES
 
   * Remove long deprecated ``Repo.commit``, ``Repo.get_blob``,
     ``Repo.tree`` and ``Repo.tag``. (Jelmer Vernooij)
 
   * Remove long deprecated ``Repo.revision_history`` and ``Repo.ref``.
     (Jelmer Vernooij)
 
   * Remove long deprecated ``Tree.entries``. (Jelmer Vernooij)
 
  BUG FIXES
 
   * Raise KeyError rather than TypeError when passing in
     unicode object of length 20 or 40 to Repo.__getitem__.
     (Jelmer Vernooij)
 
   * Use 'rm' rather than 'unlink' in tests, since the latter
     does not exist on OpenBSD and other platforms.
     (Dmitrij D. Czarkoff)
 
 0.9.4	2013-11-30
 
  IMPROVEMENTS
 
   * Add ssh_kwargs attribute to ParamikoSSHVendor. (milki)
 
   * Add Repo.set_description(). (Víðir Valberg Guðmundsson)
 
   * Add a basic `dulwich.porcelain` module. (Jelmer Vernooij, Marcin Kuzminski)
 
   * Various performance improvements for object access.
     (Jelmer Vernooij)
 
   * New function `get_transport_and_path_from_url`,
     similar to `get_transport_and_path` but only
     supports URLs.
     (Jelmer Vernooij)
 
   * Add support for file:// URLs in `get_transport_and_path_from_url`.
     (Jelmer Vernooij)
 
   * Add LocalGitClient implementation.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Support filesystems with 64bit inode and device numbers.
     (André Roth)
 
  CHANGES
 
   * Ref handling has been moved to dulwich.refs.
     (Jelmer Vernooij)
 
  API CHANGES
 
   * Remove long deprecated RefsContainer.set_ref().
     (Jelmer Vernooij)
 
   * Repo.ref() is now deprecated in favour of Repo.refs[].
     (Jelmer Vernooij)
 
 FEATURES
 
   * Add support for graftpoints. (milki)
 
 0.9.3	2013-09-27
 
  BUG FIXES
 
   * Fix path for stdint.h in MANIFEST.in. (Jelmer Vernooij)
 
 0.9.2	2013-09-26
 
  BUG FIXES
 
   * Include stdint.h in MANIFEST.in (Mark Mikofski)
 
 0.9.1	2013-09-22
 
  BUG FIXES
 
   * Support lookups of 40-character refs in BaseRepo.__getitem__. (Chow Loong Jin, Jelmer Vernooij)
 
   * Fix fetching packs with side-band-64k capability disabled. (David Keijser, Jelmer Vernooij)
 
   * Several fixes in send-pack protocol behaviour - handling of empty pack files and deletes.
     (milki, #1063087)
 
   * Fix capability negotiation when fetching packs over HTTP.
     (#1072461, William Grant)
 
   * Enforce determine_wants returning an empty list rather than None. (Fabien Boucher, Jelmer Vernooij)
 
   * In the server, support pushes just removing refs. (Fabien Boucher, Jelmer Vernooij)
 
  IMPROVEMENTS
 
   * Support passing a single revision to BaseRepo.get_walker() rather than a list of revisions. 
     (Alberto Ruiz)
 
   * Add `Repo.get_description` method. (Jelmer Vernooij)
 
   * Support thin packs in Pack.iterobjects() and Pack.get_raw().
     (William Grant)
 
   * Add `MemoryObjectStore.add_pack` and `MemoryObjectStore.add_thin_pack` methods.
     (David Bennett)
 
   * Add paramiko-based SSH vendor. (Aaron O'Mullan)
 
   * Support running 'dulwich.server' and 'dulwich.web' using 'python -m'.
     (Jelmer Vernooij)
 
   * Add ObjectStore.close(). (Jelmer Vernooij)
 
   * Raise appropriate NotImplementedError when encountering dumb HTTP servers.
     (Jelmer Vernooij)
 
  API CHANGES
 
   * SSHVendor.connect_ssh has been renamed to SSHVendor.run_command.
     (Jelmer Vernooij)
 
   * ObjectStore.add_pack() now returns a 3-tuple. The last element will be an
     abort() method that can be used to cancel the pack operation.
     (Jelmer Vernooij)
 
 0.9.0	2013-05-31
 
  BUG FIXES
 
   * Push efficiency - report missing objects only. (#562676, Artem Tikhomirov)
 
   * Use indentation consistent with C Git in config files.
     (#1031356, Curt Moore, Jelmer Vernooij)
 
   * Recognize and skip binary files in diff function.
     (Takeshi Kanemoto)
 
   * Fix handling of relative paths in dulwich.client.get_transport_and_path.
     (Brian Visel, #1169368)
 
   * Preserve ordering of entries in configuration.
     (Benjamin Pollack)
 
   * Support ~ expansion in SSH client paths. (milki, #1083439)
 
   * Support relative paths in alternate paths.
     (milki, Michel Lespinasse, #1175007)
 
   * Log all error messages from wsgiref server to the logging module. This
     makes the test suit quiet again. (Gary van der Merwe)
 
   * Support passing None for empty tree in changes_from_tree.
     (Kevin Watters)
 
   * Support fetching empty repository in client. (milki, #1060462)
 
  IMPROVEMENTS:
 
   * Add optional honor_filemode flag to build_index_from_tree.
     (Mark Mikofski)
 
   * Support core/filemode setting when building trees. (Jelmer Vernooij)
 
   * Add chapter on tags in tutorial. (Ryan Faulkner)
 
  FEATURES
 
   * Add support for mergetags. (milki, #963525)
 
   * Add support for posix shell hooks. (milki)
 
 0.8.7	2012-11-27
 
  BUG FIXES
 
   * Fix use of alternates in ``DiskObjectStore``.{__contains__,__iter__}.
     (Dmitriy)
 
   * Fix compatibility with Python 2.4. (David Carr)
 
 0.8.6	2012-11-09
 
  API CHANGES
 
   * dulwich.__init__ no longer imports client, protocol, repo and
     server modules. (Jelmer Vernooij)
 
  FEATURES
 
   * ConfigDict now behaves more like a dictionary.
     (Adam 'Cezar' Jenkins, issue #58)
 
   * HTTPGitApplication now takes an optional
     `fallback_app` argument. (Jonas Haag, issue #67)
 
   * Support for large pack index files. (Jameson Nash)
 
  TESTING
 
   * Make index entry tests a little bit less strict, to cope with
     slightly different behaviour on various platforms.
     (Jelmer Vernooij)
 
   * ``setup.py test`` (available when setuptools is installed) now
     runs all tests, not just the basic unit tests.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Commit._deserialize now actually deserializes the current state rather than
     the previous one. (Yifan Zhang, issue #59)
 
   * Handle None elements in lists of TreeChange objects. (Alex Holmes)
 
   * Support cloning repositories without HEAD set.
     (D-Key, Jelmer Vernooij, issue #69)
 
   * Support ``MemoryRepo.get_config``. (Jelmer Vernooij)
 
   * In ``get_transport_and_path``, pass extra keyword arguments on to
     HttpGitClient. (Jelmer Vernooij)
 
 0.8.5	2012-03-29
 
  BUG FIXES
 
   * Avoid use of 'with' in dulwich.index. (Jelmer Vernooij)
 
   * Be a little bit strict about OS behaviour in index tests.
     Should fix the tests on Debian GNU/kFreeBSD. (Jelmer Vernooij)
 
 0.8.4	2012-03-28
 
  BUG FIXES
 
   * Options on the same line as sections in config files are now supported.
     (Jelmer Vernooij, #920553)
 
   * Only negotiate capabilities that are also supported by the server.
     (Rod Cloutier, Risto Kankkunen)
 
   * Fix parsing of invalid timezone offsets with two minus signs.
     (Jason R. Coombs, #697828)
 
   * Reset environment variables during tests, to avoid
     test isolation leaks reading ~/.gitconfig. (Risto Kankkunen)
 
  TESTS
 
   * $HOME is now explicitly specified for tests that use it to read
     ``~/.gitconfig``, to prevent test isolation issues.
     (Jelmer Vernooij, #920330)
 
  FEATURES
 
   * Additional arguments to get_transport_and_path are now passed
     on to the constructor of the transport. (Sam Vilain)
 
   * The WSGI server now transparently handles when a git client submits data
     using Content-Encoding: gzip.
     (David Blewett, Jelmer Vernooij)
 
   * Add dulwich.index.build_index_from_tree(). (milki)
 
 0.8.3	2012-01-21
 
  FEATURES
 
   * The config parser now supports the git-config file format as
     described in git-config(1) and can write git config files.
     (Jelmer Vernooij, #531092, #768687)
 
   * ``Repo.do_commit`` will now use the user identity from
     .git/config or ~/.gitconfig if none was explicitly specified.
     (Jelmer Vernooij)
 
  BUG FIXES
 
   * Allow ``determine_wants`` methods to include the zero sha in their
     return value. (Jelmer Vernooij)
 
 0.8.2	2011-12-18
 
  BUG FIXES
 
   * Cope with different zlib buffer sizes in sha1 file parser.
     (Jelmer Vernooij)
 
   * Fix get_transport_and_path for HTTP/HTTPS URLs.
     (Bruno Renié)
 
   * Avoid calling free_objects() on NULL in error cases. (Chris Eberle)
 
   * Fix use --bare argument to 'dulwich init'. (Chris Eberle)
 
   * Properly abort connections when the determine_wants function
     raises an exception. (Jelmer Vernooij, #856769)
 
   * Tweak xcodebuild hack to deal with more error output.
     (Jelmer Vernooij, #903840)
 
  FEATURES
 
   * Add support for retrieving tarballs from remote servers.
     (Jelmer Vernooij, #379087)
 
   * New method ``update_server_info`` which generates data
     for dumb server access. (Jelmer Vernooij, #731235)
 
 0.8.1	2011-10-31
 
  FEATURES
 
   * Repo.do_commit has a new argument 'ref'.
 
   * Repo.do_commit has a new argument 'merge_heads'. (Jelmer Vernooij)
 
   * New ``Repo.get_walker`` method. (Jelmer Vernooij)
 
   * New ``Repo.clone`` method. (Jelmer Vernooij, #725369)
 
   * ``GitClient.send_pack`` now supports the 'side-band-64k' capability.
     (Jelmer Vernooij)
 
   * ``HttpGitClient`` which supports the smart server protocol over
     HTTP. "dumb" access is not yet supported. (Jelmer Vernooij, #373688)
 
   * Add basic support for alternates. (Jelmer Vernooij, #810429)
 
  CHANGES
 
   * unittest2 or python >= 2.7 is now required for the testsuite.
     testtools is no longer supported. (Jelmer Vernooij, #830713)
 
  BUG FIXES
 
   * Fix compilation with older versions of MSVC.  (Martin gz)
 
   * Special case 'refs/stash' as a valid ref. (Jelmer Vernooij, #695577)
 
   * Smart protocol clients can now change refs even if they are
     not uploading new data. (Jelmer Vernooij, #855993)
 
   * Don't compile C extensions when running in pypy.
     (Ronny Pfannschmidt, #881546)
 
   * Use different name for strnlen replacement function to avoid clashing
     with system strnlen. (Jelmer Vernooij, #880362)
 
  API CHANGES
 
   * ``Repo.revision_history`` is now deprecated in favor of ``Repo.get_walker``.
     (Jelmer Vernooij)
 
 0.8.0	2011-08-07
 
  FEATURES
 
   * New DeltaChainIterator abstract class for quickly iterating all objects in
     a pack, with implementations for pack indexing and inflation.
     (Dave Borowitz)
 
   * New walk module with a Walker class for customizable commit walking.
     (Dave Borowitz)
 
   * New tree_changes_for_merge function in diff_tree. (Dave Borowitz)
 
   * Easy rename detection in RenameDetector even without find_copies_harder.
     (Dave Borowitz)
 
  BUG FIXES
 
   * Avoid storing all objects in memory when writing pack.
     (Jelmer Vernooij, #813268)
 
   * Support IPv6 for git:// connections. (Jelmer Vernooij, #801543)
 
   * Improve performance of Repo.revision_history(). (Timo Schmid, #535118)
 
   * Fix use of SubprocessWrapper on Windows. (Paulo Madeira, #670035)
 
   * Fix compilation on newer versions of Mac OS X (Lion and up). (Ryan McKern, #794543)
 
   * Prevent raising ValueError for correct refs in RefContainer.__delitem__.
 
   * Correctly return a tuple from MemoryObjectStore.get_raw. (Dave Borowitz)
 
   * Fix a bug in reading the pack checksum when there are fewer than 20 bytes
     left in the buffer. (Dave Borowitz)
 
   * Support ~ in git:// URL paths. (Jelmer Vernooij, #813555)
 
   * Make ShaFile.__eq__ work when other is not a ShaFile. (Dave Borowitz)
 
   * ObjectStore.get_graph_walker() now no longer yields the same
     revision more than once. This has a significant improvement for
     performance when wide revision graphs are involved.
     (Jelmer Vernooij, #818168)
 
   * Teach ReceivePackHandler how to read empty packs. (Dave Borowitz)
 
   * Don't send a pack with duplicates of the same object. (Dave Borowitz)
 
   * Teach the server how to serve a clone of an empty repo. (Dave Borowitz)
 
   * Correctly advertise capabilities during receive-pack. (Dave Borowitz)
 
   * Fix add/add and add/rename conflicts in tree_changes_for_merge.
     (Dave Borowitz)
 
   * Use correct MIME types in web server. (Dave Borowitz)
 
  API CHANGES
 
   * write_pack no longer takes the num_objects argument and requires an object
     to be passed in that is iterable (rather than an iterator) and that
     provides __len__.  (Jelmer Vernooij)
 
   * write_pack_data has been renamed to write_pack_objects and no longer takes a
     num_objects argument. (Jelmer Vernooij)
 
   * take_msb_bytes, read_zlib_chunks, unpack_objects, and
     PackStreamReader.read_objects now take an additional argument indicating a
     crc32 to compute. (Dave Borowitz)
 
   * PackObjectIterator was removed; its functionality is still exposed by
     PackData.iterobjects. (Dave Borowitz)
 
   * Add a sha arg to write_pack_object to incrementally compute a SHA.
     (Dave Borowitz)
 
   * Include offset in PackStreamReader results. (Dave Borowitz)
 
   * Move PackStreamReader from server to pack. (Dave Borowitz)
 
   * Extract a check_length_and_checksum, compute_file_sha, and
     pack_object_header pack helper functions. (Dave Borowitz)
 
   * Extract a compute_file_sha function. (Dave Borowitz)
 
   * Remove move_in_thin_pack as a separate method; add_thin_pack now completes
     the thin pack and moves it in in one step. Remove ThinPackData as well.
     (Dave Borowitz)
 
   * Custom buffer size in read_zlib_chunks. (Dave Borowitz)
 
   * New UnpackedObject data class that replaces ad-hoc tuples in the return
     value of unpack_object and various DeltaChainIterator methods.
     (Dave Borowitz)
 
   * Add a lookup_path convenience method to Tree. (Dave Borowitz)
 
   * Optionally create RenameDetectors without passing in tree SHAs.
     (Dave Borowitz)
 
   * Optionally include unchanged entries in RenameDetectors. (Dave Borowitz)
 
   * Optionally pass a RenameDetector to tree_changes. (Dave Borowitz)
 
   * Optionally pass a request object through to server handlers. (Dave Borowitz)
 
  TEST CHANGES
 
   * If setuptools is installed, "python setup.py test" will now run the testsuite.
     (Jelmer Vernooij)
 
   * Add a new build_pack test utility for building packs from a simple spec.
     (Dave Borowitz)
 
   * Add a new build_commit_graph test utility for building commits from a
     simple spec. (Dave Borowitz)
 
 0.7.1	2011-04-12
 
  BUG FIXES
 
   * Fix double decref in _diff_tree.c. (Ted Horst, #715528)
 
   * Fix the build on Windows. (Pascal Quantin)
 
   * Fix get_transport_and_path compatibility with pre-2.6.5 versions of Python.
     (Max Bowsher, #707438)
 
   * BaseObjectStore.determine_wants_all no longer breaks on zero SHAs.
     (Jelmer Vernooij)
 
   * write_tree_diff() now supports submodules.
     (Jelmer Vernooij)
 
   * Fix compilation for XCode 4 and older versions of distutils.sysconfig.
     (Daniele Sluijters)
 
  IMPROVEMENTS
 
   * Sphinxified documentation. (Lukasz Balcerzak)
 
   * Add Pack.keep.(Marc Brinkmann)
 
  API CHANGES
 
   * The order of the parameters to Tree.add(name, mode, sha) has changed, and
     is now consistent with the rest of Dulwich. Existing code will still
     work but print a DeprecationWarning. (Jelmer Vernooij, #663550)
 
   * Tree.entries() is now deprecated in favour of Tree.items() and
     Tree.iteritems(). (Jelmer Vernooij)
 
 0.7.0	2011-01-21
 
  FEATURES
 
   * New `dulwich.diff_tree` module for simple content-based rename detection.
     (Dave Borowitz)
 
   * Add Tree.items(). (Jelmer Vernooij)
 
   * Add eof() and unread_pkt_line() methods to Protocol. (Dave Borowitz)
 
   * Add write_tree_diff(). (Jelmer Vernooij)
 
   * Add `serve_command` function for git server commands as executables.
     (Jelmer Vernooij)
 
   * dulwich.client.get_transport_and_path now supports rsync-style repository URLs.
     (Dave Borowitz, #568493)
 
  BUG FIXES
 
   * Correct short-circuiting operation for no-op fetches in the server.
     (Dave Borowitz)
 
   * Support parsing git mbox patches without a version tail, as generated by
     Mercurial.  (Jelmer Vernooij)
 
   * Fix dul-receive-pack and dul-upload-pack. (Jelmer Vernooij)
 
   * Zero-padded file modes in Tree objects no longer trigger an exception but
     the check code warns about them. (Augie Fackler, #581064)
 
   * Repo.init() now honors the mkdir flag. (#671159)
 
   * The ref format is now checked when setting a ref rather than when reading it back.
     (Dave Borowitz, #653527)
 
   * Make sure pack files are closed correctly. (Tay Ray Chuan)
 
  DOCUMENTATION
 
   * Run the tutorial inside the test suite. (Jelmer Vernooij)
 
   * Reorganized and updated the tutorial. (Jelmer Vernooij, Dave Borowitz, #610550,
      #610540)
 
 
 0.6.2	2010-10-16
 
  BUG FIXES
 
   * HTTP server correctly handles empty CONTENT_LENGTH. (Dave Borowitz)
 
   * Don't error when creating GitFiles with the default mode. (Dave Borowitz)
 
   * ThinPackData.from_file now works with resolve_ext_ref callback.
     (Dave Borowitz)
 
   * Provide strnlen() on mingw32 which doesn't have it. (Hans Kolek)
 
   * Set bare=true in the configuratin for bare repositories. (Dirk Neumann)
 
  FEATURES
 
   * Use slots for core objects to save up on memory. (Jelmer Vernooij)
 
   * Web server supports streaming progress/pack output. (Dave Borowitz)
 
   * New public function dulwich.pack.write_pack_header. (Dave Borowitz)
 
   * Distinguish between missing files and read errors in HTTP server.
     (Dave Borowitz)
 
   * Initial work on support for fastimport using python-fastimport.
     (Jelmer Vernooij)
 
   * New dulwich.pack.MemoryPackIndex class. (Jelmer Vernooij)
 
   * Delegate SHA peeling to the object store.  (Dave Borowitz)
 
  TESTS
 
   * Use GitFile when modifying packed-refs in tests. (Dave Borowitz)
 
   * New tests in test_web with better coverage and fewer ad-hoc mocks.
     (Dave Borowitz)
 
   * Standardize quote delimiters in test_protocol. (Dave Borowitz)
 
   * Fix use when testtools is installed. (Jelmer Vernooij)
 
   * Add trivial test for write_pack_header. (Jelmer Vernooij)
 
   * Refactor some of dulwich.tests.compat.server_utils. (Dave Borowitz)
 
   * Allow overwriting id property of objects in test utils. (Dave Borowitz)
 
   * Use real in-memory objects rather than stubs for server tests.
     (Dave Borowitz)
 
   * Clean up MissingObjectFinder. (Dave Borowitz)
 
  API CHANGES
 
   * ObjectStore.iter_tree_contents now walks contents in depth-first, sorted
     order. (Dave Borowitz)
 
   * ObjectStore.iter_tree_contents can optionally yield tree objects as well.
     (Dave Borowitz).
 
   * Add side-band-64k support to ReceivePackHandler. (Dave Borowitz)
 
   * Change server capabilities methods to classmethods. (Dave Borowitz)
 
   * Tweak server handler injection. (Dave Borowitz)
 
   * PackIndex1 and PackIndex2 now subclass FilePackIndex, which is 
     itself a subclass of PackIndex. (Jelmer Vernooij)
 
  DOCUMENTATION
 
   * Add docstrings for various functions in dulwich.objects. (Jelmer Vernooij)
 
   * Clean up docstrings in dulwich.protocol. (Dave Borowitz)
 
   * Explicitly specify allowed protocol commands to
     ProtocolGraphWalker.read_proto_line.  (Dave Borowitz)
 
   * Add utility functions to DictRefsContainer. (Dave Borowitz)
 
 
 0.6.1	2010-07-22
 
  BUG FIXES
 
   * Fix memory leak in C implementation of sorted_tree_items. (Dave Borowitz)
 
   * Use correct path separators for named repo files. (Dave Borowitz)
 
   * python > 2.7 and testtools-based test runners will now also pick up skipped
     tests correctly. (Jelmer Vernooij)
 
  FEATURES
 
   * Move named file initilization to BaseRepo. (Dave Borowitz)
 
   * Add logging utilities and git/HTTP server logging. (Dave Borowitz)
 
   * The GitClient interface has been cleaned up and instances are now reusable.
     (Augie Fackler)
 
   * Allow overriding paths to executables in GitSSHClient. 
     (Ross Light, Jelmer Vernooij, #585204)
 
   * Add PackBasedObjectStore.pack_loose_objects(). (Jelmer Vernooij)
 
  TESTS
 
   * Add tests for sorted_tree_items and C implementation. (Dave Borowitz)
 
   * Add a MemoryRepo that stores everything in memory. (Dave Borowitz)
 
   * Quiet logging output from web tests. (Dave Borowitz)
 
   * More flexible version checking for compat tests. (Dave Borowitz)
 
   * Compat tests for servers with and without side-band-64k. (Dave Borowitz)
 
  CLEANUP
 
   * Clean up file headers. (Dave Borowitz)
 
  TESTS
 
   * Use GitFile when modifying packed-refs in tests. (Dave Borowitz)
 
  API CHANGES
 
   * dulwich.pack.write_pack_index_v{1,2} now take a file-like object
     rather than a filename. (Jelmer Vernooij)
 
   * Make dul-daemon/dul-web trivial wrappers around server functionality.
     (Dave Borowitz)
 
   * Move reference WSGI handler to web.py. (Dave Borowitz)
 
   * Factor out _report_status in ReceivePackHandler. (Dave Borowitz)
 
   * Factor out a function to convert a line to a pkt-line. (Dave Borowitz)
 
 
 0.6.0	2010-05-22
 
 note: This list is most likely incomplete for 0.6.0.
 
  BUG FIXES
  
   * Fix ReceivePackHandler to disallow removing refs without delete-refs.
     (Dave Borowitz)
 
   * Deal with capabilities required by the client, even if they 
     can not be disabled in the server. (Dave Borowitz)
 
   * Fix trailing newlines in generated patch files.
     (Jelmer Vernooij)
 
   * Implement RefsContainer.__contains__. (Jelmer Vernooij)
 
   * Cope with \r in ref files on Windows. (
     http://github.com/jelmer/dulwich/issues/#issue/13, Jelmer Vernooij)
 
   * Fix GitFile breakage on Windows. (Anatoly Techtonik, #557585)
 
   * Support packed ref deletion with no peeled refs. (Augie Fackler)
 
   * Fix send pack when there is nothing to fetch. (Augie Fackler)
 
   * Fix fetch if no progress function is specified. (Augie Fackler)
 
   * Allow double-staging of files that are deleted in the index. 
     (Dave Borowitz)
 
   * Fix RefsContainer.add_if_new to support dangling symrefs.
     (Dave Borowitz)
 
   * Non-existant index files in non-bare repositories are now treated as 
     empty. (Dave Borowitz)
 
   * Always update ShaFile.id when the contents of the object get changed. 
     (Jelmer Vernooij)
 
   * Various Python2.4-compatibility fixes. (Dave Borowitz)
 
   * Fix thin pack handling. (Dave Borowitz)
  
  FEATURES
 
   * Add include-tag capability to server. (Dave Borowitz)
 
   * New dulwich.fastexport module that can generate fastexport 
     streams. (Jelmer Vernooij)
 
   * Implemented BaseRepo.__contains__. (Jelmer Vernooij)
 
   * Add __setitem__ to DictRefsContainer. (Dave Borowitz)
 
   * Overall improvements checking Git objects. (Dave Borowitz)
 
   * Packs are now verified while they are received. (Dave Borowitz)
 
  TESTS
 
   * Add framework for testing compatibility with C Git. (Dave Borowitz)
 
   * Add various tests for the use of non-bare repositories. (Dave Borowitz)
 
   * Cope with diffstat not being available on all platforms. 
     (Tay Ray Chuan, Jelmer Vernooij)
 
   * Add make_object and make_commit convenience functions to test utils.
     (Dave Borowitz)
 
  API BREAKAGES
 
   * The 'committer' and 'message' arguments to Repo.do_commit() have 
     been swapped. 'committer' is now optional. (Jelmer Vernooij)
 
   * Repo.get_blob, Repo.commit, Repo.tag and Repo.tree are now deprecated.
     (Jelmer Vernooij)
 
   * RefsContainer.set_ref() was renamed to RefsContainer.set_symbolic_ref(),
     for clarity. (Jelmer Vernooij)
 
  API CHANGES
 
   * The primary serialization APIs in dulwich.objects now work 
     with chunks of strings rather than with full-text strings. 
     (Jelmer Vernooij)
 
 0.5.02010-03-03
 
  BUG FIXES
 
   * Support custom fields in commits (readonly). (Jelmer Vernooij)
 
   * Improved ref handling. (Dave Borowitz)
 
   * Rework server protocol to be smarter and interoperate with cgit client.
     (Dave Borowitz)
 
   * Add a GitFile class that uses the same locking protocol for writes as 
     cgit. (Dave Borowitz)
 
   * Cope with forward slashes correctly in the index on Windows.
     (Jelmer Vernooij, #526793)
 
  FEATURES
 
   * --pure option to setup.py to allow building/installing without the C 
     extensions. (Hal Wine, Anatoly Techtonik, Jelmer Vernooij, #434326)
 
   * Implement Repo.get_config(). (Jelmer Vernooij, Augie Fackler)
 
   * HTTP dumb and smart server. (Dave Borowitz)
 
   * Add abstract baseclass for Repo that does not require file system 
     operations. (Dave Borowitz)
 
 0.4.1	2010-01-03
 
  FEATURES
 
   * Add ObjectStore.iter_tree_contents(). (Jelmer Vernooij)
 
   * Add Index.changes_from_tree(). (Jelmer Vernooij)
 
   * Add ObjectStore.tree_changes(). (Jelmer Vernooij)
 
   * Add functionality for writing patches in dulwich.patch.
     (Jelmer Vernooij)
 
 0.4.0	2009-10-07
 
  DOCUMENTATION
 
   * Added tutorial.
 
  API CHANGES
 
   * dulwich.object_store.tree_lookup_path will now return the mode and 
     sha of the object found rather than the object itself.
 
  BUG FIXES
 
   * Use binascii.hexlify / binascii.unhexlify for better performance.
 
   * Cope with extra unknown data in index files by ignoring it (for now).
 
   * Add proper error message when server unexpectedly hangs up. (#415843)
 
   * Correctly write opcode for equal in create_delta.
 
 0.3.3	2009-07-23
 
  FEATURES
 
   * Implement ShaFile.__hash__().
 
   * Implement Tree.__len__()
 
  BUG FIXES
   
   * Check for 'objects' and 'refs' directories
     when looking for a Git repository. (#380818)
 
 0.3.2	2009-05-20
 
  BUG FIXES
 
   * Support the encoding field in Commits.
   
   * Some Windows compatibility fixes.
 
   * Fixed several issues in commit support.
 
  FEATURES
 
   * Basic support for handling submodules.
 
 0.3.1	2009-05-13
 
  FEATURES
 
   * Implemented Repo.__getitem__, Repo.__setitem__ and Repo.__delitem__ to 
     access content.
 
  API CHANGES
 
   * Removed Repo.set_ref, Repo.remove_ref, Repo.tags, Repo.get_refs and 
     Repo.heads in favor of Repo.refs, a dictionary-like object for accessing
     refs.
 
  BUG FIXES
 
   * Removed import of 'sha' module in objects.py, which was causing 
     deprecation warnings on Python 2.6.
 
 0.3.0	2009-05-10
 
  FEATURES
 
   * A new function 'commit_tree' has been added that can commit a tree 
     based on an index.
 
  BUG FIXES
 
   * The memory usage when generating indexes has been significantly reduced.
  
   * A memory leak in the C implementation of parse_tree has been fixed.
 
   * The send-pack smart server command now works. (Thanks Scott Chacon)
 
   * The handling of short timestamps (less than 10 digits) has been fixed.
 
   * The handling of timezones has been fixed.
 
 0.2.1	2009-04-30
 
  BUG FIXES
 
   * Fix compatibility with Python2.4.
 
 0.2.0	2009-04-30
 
  FEATURES
 
   * Support for activity reporting in smart protocol client.
 
   * Optional C extensions for better performance in a couple of 
     places that are performance-critical.
 
 0.1.1	2009-03-13
 
  BUG FIXES
 
   * Fixed regression in Repo.find_missing_objects()
 
   * Don't fetch ^{} objects from remote hosts, as requesting them 
     causes a hangup.
 
   * Always write pack to disk completely before calculating checksum.
 
  FEATURES
 
   * Allow disabling thin packs when talking to remote hosts.
 
 0.1.0	2009-01-24
 
   * Initial release.
diff --git a/dulwich/client.py b/dulwich/client.py
index e1edff8c..2527853c 100644
--- a/dulwich/client.py
+++ b/dulwich/client.py
@@ -1,2209 +1,2238 @@
 # client.py -- Implementation of the client side git protocols
 # Copyright (C) 2008-2013 Jelmer Vernooij <jelmer@jelmer.uk>
 #
 # Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
 # General Public License as public by the Free Software Foundation; version 2.0
 # or (at your option) any later version. You can redistribute it and/or
 # modify it under the terms of either of these two licenses.
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
 # You should have received a copy of the licenses; if not, see
 # <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
 # and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
 # License, Version 2.0.
 #
 
 """Client side support for the Git protocol.
 
 The Dulwich client supports the following capabilities:
 
  * thin-pack
  * multi_ack_detailed
  * multi_ack
  * side-band-64k
  * ofs-delta
  * quiet
  * report-status
  * delete-refs
  * shallow
 
 Known capabilities that are not supported:
 
  * no-progress
  * include-tag
 """
 
 from contextlib import closing
 from io import BytesIO, BufferedReader
 import logging
 import os
 import select
 import socket
 import subprocess
 import sys
 from typing import Optional, Dict, Callable, Set
 
 from urllib.parse import (
     quote as urlquote,
     unquote as urlunquote,
     urlparse,
     urljoin,
     urlunsplit,
     urlunparse,
 )
 
 import dulwich
 from dulwich.config import get_xdg_config_home_path
 from dulwich.errors import (
     GitProtocolError,
     NotGitRepository,
     SendPackError,
 )
 from dulwich.protocol import (
     HangupException,
     _RBUFSIZE,
     agent_string,
     capability_agent,
     extract_capability_names,
     CAPABILITY_AGENT,
     CAPABILITY_DELETE_REFS,
     CAPABILITY_INCLUDE_TAG,
     CAPABILITY_MULTI_ACK,
     CAPABILITY_MULTI_ACK_DETAILED,
     CAPABILITY_OFS_DELTA,
     CAPABILITY_QUIET,
     CAPABILITY_REPORT_STATUS,
     CAPABILITY_SHALLOW,
     CAPABILITY_SYMREF,
     CAPABILITY_SIDE_BAND_64K,
     CAPABILITY_THIN_PACK,
     CAPABILITIES_REF,
     KNOWN_RECEIVE_CAPABILITIES,
     KNOWN_UPLOAD_CAPABILITIES,
     COMMAND_DEEPEN,
     COMMAND_SHALLOW,
     COMMAND_UNSHALLOW,
     COMMAND_DONE,
     COMMAND_HAVE,
     COMMAND_WANT,
     SIDE_BAND_CHANNEL_DATA,
     SIDE_BAND_CHANNEL_PROGRESS,
     SIDE_BAND_CHANNEL_FATAL,
     PktLineParser,
     Protocol,
     ProtocolFile,
     TCP_GIT_PORT,
     ZERO_SHA,
     extract_capabilities,
     parse_capability,
 )
 from dulwich.pack import (
     write_pack_data,
     write_pack_objects,
 )
 from dulwich.refs import (
     read_info_refs,
     ANNOTATED_TAG_SUFFIX,
 )
 
 
 logger = logging.getLogger(__name__)
 
 
 class InvalidWants(Exception):
     """Invalid wants."""
 
     def __init__(self, wants):
         Exception.__init__(
             self, "requested wants not in server provided refs: %r" % wants
         )
 
 
 class HTTPUnauthorized(Exception):
     """Raised when authentication fails."""
 
     def __init__(self, www_authenticate, url):
         Exception.__init__(self, "No valid credentials provided")
         self.www_authenticate = www_authenticate
         self.url = url
 
 
 class HTTPProxyUnauthorized(Exception):
     """Raised when proxy authentication fails."""
 
     def __init__(self, proxy_authenticate, url):
         Exception.__init__(self, "No valid proxy credentials provided")
         self.proxy_authenticate = proxy_authenticate
         self.url = url
 
 
 def _fileno_can_read(fileno):
     """Check if a file descriptor is readable."""
     return len(select.select([fileno], [], [], 0)[0]) > 0
 
 
 def _win32_peek_avail(handle):
     """Wrapper around PeekNamedPipe to check how many bytes are available."""
     from ctypes import byref, wintypes, windll
 
     c_avail = wintypes.DWORD()
     c_message = wintypes.DWORD()
     success = windll.kernel32.PeekNamedPipe(
         handle, None, 0, None, byref(c_avail), byref(c_message)
     )
     if not success:
         raise OSError(wintypes.GetLastError())
     return c_avail.value
 
 
 COMMON_CAPABILITIES = [CAPABILITY_OFS_DELTA, CAPABILITY_SIDE_BAND_64K]
 UPLOAD_CAPABILITIES = [
     CAPABILITY_THIN_PACK,
     CAPABILITY_MULTI_ACK,
     CAPABILITY_MULTI_ACK_DETAILED,
     CAPABILITY_SHALLOW,
 ] + COMMON_CAPABILITIES
 RECEIVE_CAPABILITIES = [
     CAPABILITY_REPORT_STATUS,
     CAPABILITY_DELETE_REFS,
 ] + COMMON_CAPABILITIES
 
 
 class ReportStatusParser(object):
     """Handle status as reported by servers with 'report-status' capability."""
 
     def __init__(self):
         self._done = False
         self._pack_status = None
         self._ref_statuses = []
 
     def check(self):
         """Check if there were any errors and, if so, raise exceptions.
 
         Raises:
           SendPackError: Raised when the server could not unpack
         Returns:
           iterator over refs
         """
         if self._pack_status not in (b"unpack ok", None):
             raise SendPackError(self._pack_status)
         for status in self._ref_statuses:
             try:
                 status, rest = status.split(b" ", 1)
             except ValueError:
                 # malformed response, move on to the next one
                 continue
             if status == b"ng":
                 ref, error = rest.split(b" ", 1)
                 yield ref, error.decode("utf-8")
             elif status == b"ok":
                 yield rest, None
             else:
                 raise GitProtocolError("invalid ref status %r" % status)
 
     def handle_packet(self, pkt):
         """Handle a packet.
 
         Raises:
           GitProtocolError: Raised when packets are received after a flush
           packet.
         """
         if self._done:
             raise GitProtocolError("received more data after status report")
         if pkt is None:
             self._done = True
             return
         if self._pack_status is None:
             self._pack_status = pkt.strip()
         else:
             ref_status = pkt.strip()
             self._ref_statuses.append(ref_status)
 
 
 def read_pkt_refs(proto):
     server_capabilities = None
     refs = {}
     # Receive refs from server
     for pkt in proto.read_pkt_seq():
         (sha, ref) = pkt.rstrip(b"\n").split(None, 1)
         if sha == b"ERR":
             raise GitProtocolError(ref.decode("utf-8", "replace"))
         if server_capabilities is None:
             (ref, server_capabilities) = extract_capabilities(ref)
         refs[ref] = sha
 
     if len(refs) == 0:
         return {}, set([])
     if refs == {CAPABILITIES_REF: ZERO_SHA}:
         refs = {}
     return refs, set(server_capabilities)
 
 
 class FetchPackResult(object):
     """Result of a fetch-pack operation.
 
     Attributes:
       refs: Dictionary with all remote refs
       symrefs: Dictionary with remote symrefs
       agent: User agent string
     """
 
     _FORWARDED_ATTRS = [
         "clear",
         "copy",
         "fromkeys",
         "get",
         "items",
         "keys",
         "pop",
         "popitem",
         "setdefault",
         "update",
         "values",
         "viewitems",
         "viewkeys",
         "viewvalues",
     ]
 
     def __init__(self, refs, symrefs, agent, new_shallow=None, new_unshallow=None):
         self.refs = refs
         self.symrefs = symrefs
         self.agent = agent
         self.new_shallow = new_shallow
         self.new_unshallow = new_unshallow
 
     def _warn_deprecated(self):
         import warnings
 
         warnings.warn(
             "Use FetchPackResult.refs instead.",
             DeprecationWarning,
             stacklevel=3,
         )
 
     def __eq__(self, other):
         if isinstance(other, dict):
             self._warn_deprecated()
             return self.refs == other
         return (
             self.refs == other.refs
             and self.symrefs == other.symrefs
             and self.agent == other.agent
         )
 
     def __contains__(self, name):
         self._warn_deprecated()
         return name in self.refs
 
     def __getitem__(self, name):
         self._warn_deprecated()
         return self.refs[name]
 
     def __len__(self):
         self._warn_deprecated()
         return len(self.refs)
 
     def __iter__(self):
         self._warn_deprecated()
         return iter(self.refs)
 
     def __getattribute__(self, name):
         if name in type(self)._FORWARDED_ATTRS:
             self._warn_deprecated()
             return getattr(self.refs, name)
         return super(FetchPackResult, self).__getattribute__(name)
 
     def __repr__(self):
         return "%s(%r, %r, %r)" % (
             self.__class__.__name__,
             self.refs,
             self.symrefs,
             self.agent,
         )
 
 
 class SendPackResult(object):
     """Result of a upload-pack operation.
 
     Attributes:
       refs: Dictionary with all remote refs
       agent: User agent string
       ref_status: Optional dictionary mapping ref name to error message (if it
         failed to update), or None if it was updated successfully
     """
 
     _FORWARDED_ATTRS = [
         "clear",
         "copy",
         "fromkeys",
         "get",
         "items",
         "keys",
         "pop",
         "popitem",
         "setdefault",
         "update",
         "values",
         "viewitems",
         "viewkeys",
         "viewvalues",
     ]
 
     def __init__(self, refs, agent=None, ref_status=None):
         self.refs = refs
         self.agent = agent
         self.ref_status = ref_status
 
     def _warn_deprecated(self):
         import warnings
 
         warnings.warn(
             "Use SendPackResult.refs instead.",
             DeprecationWarning,
             stacklevel=3,
         )
 
     def __eq__(self, other):
         if isinstance(other, dict):
             self._warn_deprecated()
             return self.refs == other
         return self.refs == other.refs and self.agent == other.agent
 
     def __contains__(self, name):
         self._warn_deprecated()
         return name in self.refs
 
     def __getitem__(self, name):
         self._warn_deprecated()
         return self.refs[name]
 
     def __len__(self):
         self._warn_deprecated()
         return len(self.refs)
 
     def __iter__(self):
         self._warn_deprecated()
         return iter(self.refs)
 
     def __getattribute__(self, name):
         if name in type(self)._FORWARDED_ATTRS:
             self._warn_deprecated()
             return getattr(self.refs, name)
         return super(SendPackResult, self).__getattribute__(name)
 
     def __repr__(self):
         return "%s(%r, %r)" % (self.__class__.__name__, self.refs, self.agent)
 
 
 def _read_shallow_updates(proto):
     new_shallow = set()
     new_unshallow = set()
     for pkt in proto.read_pkt_seq():
         cmd, sha = pkt.split(b" ", 1)
         if cmd == COMMAND_SHALLOW:
             new_shallow.add(sha.strip())
         elif cmd == COMMAND_UNSHALLOW:
             new_unshallow.add(sha.strip())
         else:
             raise GitProtocolError("unknown command %s" % pkt)
     return (new_shallow, new_unshallow)
 
 
 # TODO(durin42): this doesn't correctly degrade if the server doesn't
 # support some capabilities. This should work properly with servers
 # that don't support multi_ack.
 class GitClient(object):
     """Git smart server client."""
 
     def __init__(
         self,
         thin_packs=True,
         report_activity=None,
         quiet=False,
         include_tags=False,
     ):
         """Create a new GitClient instance.
 
         Args:
           thin_packs: Whether or not thin packs should be retrieved
           report_activity: Optional callback for reporting transport
             activity.
           include_tags: send annotated tags when sending the objects they point
             to
         """
         self._report_activity = report_activity
         self._report_status_parser = None
         self._fetch_capabilities = set(UPLOAD_CAPABILITIES)
         self._fetch_capabilities.add(capability_agent())
         self._send_capabilities = set(RECEIVE_CAPABILITIES)
         self._send_capabilities.add(capability_agent())
         if quiet:
             self._send_capabilities.add(CAPABILITY_QUIET)
         if not thin_packs:
             self._fetch_capabilities.remove(CAPABILITY_THIN_PACK)
         if include_tags:
             self._fetch_capabilities.add(CAPABILITY_INCLUDE_TAG)
 
     def get_url(self, path):
         """Retrieves full url to given path.
 
         Args:
           path: Repository path (as string)
 
         Returns:
           Url to path (as string)
 
         """
         raise NotImplementedError(self.get_url)
 
     @classmethod
     def from_parsedurl(cls, parsedurl, **kwargs):
         """Create an instance of this client from a urlparse.parsed object.
 
         Args:
           parsedurl: Result of urlparse()
 
         Returns:
           A `GitClient` object
         """
         raise NotImplementedError(cls.from_parsedurl)
 
     def send_pack(self, path, update_refs, generate_pack_data, progress=None):
         """Upload a pack to a remote repository.
 
         Args:
           path: Repository path (as bytestring)
           update_refs: Function to determine changes to remote refs. Receive
             dict with existing remote refs, returns dict with
             changed refs (name -> sha, where sha=ZERO_SHA for deletions)
           generate_pack_data: Function that can return a tuple
             with number of objects and list of pack data to include
           progress: Optional progress function
 
         Returns:
           SendPackResult object
 
         Raises:
           SendPackError: if server rejects the pack data
 
         """
         raise NotImplementedError(self.send_pack)
 
     def fetch(self, path, target, determine_wants=None, progress=None, depth=None):
         """Fetch into a target repository.
 
         Args:
           path: Path to fetch from (as bytestring)
           target: Target repository to fetch into
           determine_wants: Optional function to determine what refs to fetch.
             Receives dictionary of name->sha, should return
             list of shas to fetch. Defaults to all shas.
           progress: Optional progress function
           depth: Depth to fetch at
 
         Returns:
           Dictionary with all remote refs (not just those fetched)
 
         """
         if determine_wants is None:
             determine_wants = target.object_store.determine_wants_all
         if CAPABILITY_THIN_PACK in self._fetch_capabilities:
             # TODO(jelmer): Avoid reading entire file into memory and
             # only processing it after the whole file has been fetched.
             f = BytesIO()
 
             def commit():
                 if f.tell():
                     f.seek(0)
                     target.object_store.add_thin_pack(f.read, None)
 
             def abort():
                 pass
 
         else:
             f, commit, abort = target.object_store.add_pack()
         try:
             result = self.fetch_pack(
                 path,
                 determine_wants,
                 target.get_graph_walker(),
                 f.write,
                 progress=progress,
                 depth=depth,
             )
         except BaseException:
             abort()
             raise
         else:
             commit()
         target.update_shallow(result.new_shallow, result.new_unshallow)
         return result
 
     def fetch_pack(
         self,
         path,
         determine_wants,
         graph_walker,
         pack_data,
         progress=None,
         depth=None,
     ):
         """Retrieve a pack from a git smart server.
 
         Args:
           path: Remote path to fetch from
           determine_wants: Function determine what refs
             to fetch. Receives dictionary of name->sha, should return
             list of shas to fetch.
           graph_walker: Object with next() and ack().
           pack_data: Callback called for each bit of data in the pack
           progress: Callback for progress reports (strings)
           depth: Shallow fetch depth
 
         Returns:
           FetchPackResult object
 
         """
         raise NotImplementedError(self.fetch_pack)
 
     def get_refs(self, path):
         """Retrieve the current refs from a git smart server.
 
         Args:
           path: Path to the repo to fetch from. (as bytestring)
 
         Returns:
 
         """
         raise NotImplementedError(self.get_refs)
 
     def _read_side_band64k_data(self, proto, channel_callbacks):
         """Read per-channel data.
 
         This requires the side-band-64k capability.
 
         Args:
           proto: Protocol object to read from
           channel_callbacks: Dictionary mapping channels to packet
             handlers to use. None for a callback discards channel data.
         """
         for pkt in proto.read_pkt_seq():
             channel = ord(pkt[:1])
             pkt = pkt[1:]
             try:
                 cb = channel_callbacks[channel]
             except KeyError:
                 raise AssertionError("Invalid sideband channel %d" % channel)
             else:
                 if cb is not None:
                     cb(pkt)
 
     @staticmethod
     def _should_send_pack(new_refs):
         # The packfile MUST NOT be sent if the only command used is delete.
         return any(sha != ZERO_SHA for sha in new_refs.values())
 
     def _handle_receive_pack_head(self, proto, capabilities, old_refs, new_refs):
         """Handle the head of a 'git-receive-pack' request.
 
         Args:
           proto: Protocol object to read from
           capabilities: List of negotiated capabilities
           old_refs: Old refs, as received from the server
           new_refs: Refs to change
 
         Returns:
           (have, want) tuple
         """
         want = []
         have = [x for x in old_refs.values() if not x == ZERO_SHA]
         sent_capabilities = False
 
         for refname in new_refs:
             if not isinstance(refname, bytes):
                 raise TypeError("refname is not a bytestring: %r" % refname)
             old_sha1 = old_refs.get(refname, ZERO_SHA)
             if not isinstance(old_sha1, bytes):
                 raise TypeError(
                     "old sha1 for %s is not a bytestring: %r" % (refname, old_sha1)
                 )
             new_sha1 = new_refs.get(refname, ZERO_SHA)
             if not isinstance(new_sha1, bytes):
                 raise TypeError(
                     "old sha1 for %s is not a bytestring %r" % (refname, new_sha1)
                 )
 
             if old_sha1 != new_sha1:
                 logger.debug(
                     'Sending updated ref %r: %r -> %r',
                     refname, old_sha1, new_sha1)
                 if sent_capabilities:
                     proto.write_pkt_line(old_sha1 + b" " + new_sha1 + b" " + refname)
                 else:
                     proto.write_pkt_line(
                         old_sha1
                         + b" "
                         + new_sha1
                         + b" "
                         + refname
                         + b"\0"
                         + b" ".join(sorted(capabilities))
                     )
                     sent_capabilities = True
             if new_sha1 not in have and new_sha1 != ZERO_SHA:
                 want.append(new_sha1)
         proto.write_pkt_line(None)
         return (have, want)
 
     def _negotiate_receive_pack_capabilities(self, server_capabilities):
         negotiated_capabilities = self._send_capabilities & server_capabilities
         agent = None
         for capability in server_capabilities:
             k, v = parse_capability(capability)
             if k == CAPABILITY_AGENT:
                 agent = v
         unknown_capabilities = (  # noqa: F841
             extract_capability_names(server_capabilities) - KNOWN_RECEIVE_CAPABILITIES
         )
         # TODO(jelmer): warn about unknown capabilities
         return negotiated_capabilities, agent
 
     def _handle_receive_pack_tail(
         self,
         proto: Protocol,
         capabilities: Set[bytes],
         progress: Callable[[bytes], None] = None,
     ) -> Optional[Dict[bytes, Optional[str]]]:
         """Handle the tail of a 'git-receive-pack' request.
 
         Args:
           proto: Protocol object to read from
           capabilities: List of negotiated capabilities
           progress: Optional progress reporting function
 
         Returns:
           dict mapping ref name to:
             error message if the ref failed to update
             None if it was updated successfully
         """
         if CAPABILITY_SIDE_BAND_64K in capabilities:
             if progress is None:
 
                 def progress(x):
                     pass
 
             channel_callbacks = {2: progress}
             if CAPABILITY_REPORT_STATUS in capabilities:
                 channel_callbacks[1] = PktLineParser(
                     self._report_status_parser.handle_packet
                 ).parse
             self._read_side_band64k_data(proto, channel_callbacks)
         else:
             if CAPABILITY_REPORT_STATUS in capabilities:
                 for pkt in proto.read_pkt_seq():
                     self._report_status_parser.handle_packet(pkt)
         if self._report_status_parser is not None:
             return dict(self._report_status_parser.check())
 
         return None
 
     def _negotiate_upload_pack_capabilities(self, server_capabilities):
         unknown_capabilities = (  # noqa: F841
             extract_capability_names(server_capabilities) - KNOWN_UPLOAD_CAPABILITIES
         )
         # TODO(jelmer): warn about unknown capabilities
         symrefs = {}
         agent = None
         for capability in server_capabilities:
             k, v = parse_capability(capability)
             if k == CAPABILITY_SYMREF:
                 (src, dst) = v.split(b":", 1)
                 symrefs[src] = dst
             if k == CAPABILITY_AGENT:
                 agent = v
 
         negotiated_capabilities = self._fetch_capabilities & server_capabilities
         return (negotiated_capabilities, symrefs, agent)
 
     def _handle_upload_pack_head(
         self, proto, capabilities, graph_walker, wants, can_read, depth
     ):
         """Handle the head of a 'git-upload-pack' request.
 
         Args:
           proto: Protocol object to read from
           capabilities: List of negotiated capabilities
           graph_walker: GraphWalker instance to call .ack() on
           wants: List of commits to fetch
           can_read: function that returns a boolean that indicates
         whether there is extra graph data to read on proto
           depth: Depth for request
 
         Returns:
 
         """
         assert isinstance(wants, list) and isinstance(wants[0], bytes)
         proto.write_pkt_line(
             COMMAND_WANT
             + b" "
             + wants[0]
             + b" "
             + b" ".join(sorted(capabilities))
             + b"\n"
         )
         for want in wants[1:]:
             proto.write_pkt_line(COMMAND_WANT + b" " + want + b"\n")
         if depth not in (0, None) or getattr(graph_walker, "shallow", None):
             if CAPABILITY_SHALLOW not in capabilities:
                 raise GitProtocolError(
                     "server does not support shallow capability required for " "depth"
                 )
             for sha in graph_walker.shallow:
                 proto.write_pkt_line(COMMAND_SHALLOW + b" " + sha + b"\n")
             if depth is not None:
                 proto.write_pkt_line(
                     COMMAND_DEEPEN + b" " + str(depth).encode("ascii") + b"\n"
                 )
             proto.write_pkt_line(None)
             if can_read is not None:
                 (new_shallow, new_unshallow) = _read_shallow_updates(proto)
             else:
                 new_shallow = new_unshallow = None
         else:
             new_shallow = new_unshallow = set()
             proto.write_pkt_line(None)
         have = next(graph_walker)
         while have:
             proto.write_pkt_line(COMMAND_HAVE + b" " + have + b"\n")
             if can_read is not None and can_read():
                 pkt = proto.read_pkt_line()
                 parts = pkt.rstrip(b"\n").split(b" ")
                 if parts[0] == b"ACK":
                     graph_walker.ack(parts[1])
                     if parts[2] in (b"continue", b"common"):
                         pass
                     elif parts[2] == b"ready":
                         break
                     else:
                         raise AssertionError(
                             "%s not in ('continue', 'ready', 'common)" % parts[2]
                         )
             have = next(graph_walker)
         proto.write_pkt_line(COMMAND_DONE + b"\n")
         return (new_shallow, new_unshallow)
 
     def _handle_upload_pack_tail(
         self,
         proto,
         capabilities,
         graph_walker,
         pack_data,
         progress=None,
         rbufsize=_RBUFSIZE,
     ):
         """Handle the tail of a 'git-upload-pack' request.
 
         Args:
           proto: Protocol object to read from
           capabilities: List of negotiated capabilities
           graph_walker: GraphWalker instance to call .ack() on
           pack_data: Function to call with pack data
           progress: Optional progress reporting function
           rbufsize: Read buffer size
 
         Returns:
 
         """
         pkt = proto.read_pkt_line()
         while pkt:
             parts = pkt.rstrip(b"\n").split(b" ")
             if parts[0] == b"ACK":
                 graph_walker.ack(parts[1])
             if len(parts) < 3 or parts[2] not in (
                 b"ready",
                 b"continue",
                 b"common",
             ):
                 break
             pkt = proto.read_pkt_line()
         if CAPABILITY_SIDE_BAND_64K in capabilities:
             if progress is None:
                 # Just ignore progress data
 
                 def progress(x):
                     pass
 
             self._read_side_band64k_data(
                 proto,
                 {
                     SIDE_BAND_CHANNEL_DATA: pack_data,
                     SIDE_BAND_CHANNEL_PROGRESS: progress,
                 },
             )
         else:
             while True:
                 data = proto.read(rbufsize)
                 if data == b"":
                     break
                 pack_data(data)
 
 
 def check_wants(wants, refs):
     """Check that a set of wants is valid.
 
     Args:
       wants: Set of object SHAs to fetch
       refs: Refs dictionary to check against
 
     Returns:
 
     """
     missing = set(wants) - {
         v for (k, v) in refs.items() if not k.endswith(ANNOTATED_TAG_SUFFIX)
     }
     if missing:
         raise InvalidWants(missing)
 
 
 def _remote_error_from_stderr(stderr):
     if stderr is None:
         return HangupException()
     lines = [line.rstrip(b"\n") for line in stderr.readlines()]
     for line in lines:
         if line.startswith(b"ERROR: "):
             return GitProtocolError(line[len(b"ERROR: ") :].decode("utf-8", "replace"))
     return HangupException(lines)
 
 
 class TraditionalGitClient(GitClient):
     """Traditional Git client."""
 
     DEFAULT_ENCODING = "utf-8"
 
     def __init__(self, path_encoding=DEFAULT_ENCODING, **kwargs):
         self._remote_path_encoding = path_encoding
         super(TraditionalGitClient, self).__init__(**kwargs)
 
     async def _connect(self, cmd, path):
         """Create a connection to the server.
 
         This method is abstract - concrete implementations should
         implement their own variant which connects to the server and
         returns an initialized Protocol object with the service ready
         for use and a can_read function which may be used to see if
         reads would block.
 
         Args:
           cmd: The git service name to which we should connect.
           path: The path we should pass to the service. (as bytestirng)
         """
         raise NotImplementedError()
 
     def send_pack(self, path, update_refs, generate_pack_data, progress=None):
         """Upload a pack to a remote repository.
 
         Args:
           path: Repository path (as bytestring)
           update_refs: Function to determine changes to remote refs.
             Receive dict with existing remote refs, returns dict with
             changed refs (name -> sha, where sha=ZERO_SHA for deletions)
           generate_pack_data: Function that can return a tuple with
             number of objects and pack data to upload.
           progress: Optional callback called with progress updates
 
         Returns:
           SendPackResult
 
         Raises:
           SendPackError: if server rejects the pack data
 
         """
         proto, unused_can_read, stderr = self._connect(b"receive-pack", path)
         with proto:
             try:
                 old_refs, server_capabilities = read_pkt_refs(proto)
             except HangupException:
                 raise _remote_error_from_stderr(stderr)
             (
                 negotiated_capabilities,
                 agent,
             ) = self._negotiate_receive_pack_capabilities(server_capabilities)
             if CAPABILITY_REPORT_STATUS in negotiated_capabilities:
                 self._report_status_parser = ReportStatusParser()
             report_status_parser = self._report_status_parser
 
             try:
                 new_refs = orig_new_refs = update_refs(dict(old_refs))
             except BaseException:
                 proto.write_pkt_line(None)
                 raise
 
             if set(new_refs.items()).issubset(set(old_refs.items())):
                 proto.write_pkt_line(None)
                 return SendPackResult(new_refs, agent=agent, ref_status={})
 
             if CAPABILITY_DELETE_REFS not in server_capabilities:
                 # Server does not support deletions. Fail later.
                 new_refs = dict(orig_new_refs)
                 for ref, sha in orig_new_refs.items():
                     if sha == ZERO_SHA:
                         if CAPABILITY_REPORT_STATUS in negotiated_capabilities:
                             report_status_parser._ref_statuses.append(
                                 b"ng " + ref + b" remote does not support deleting refs"
                             )
                             report_status_parser._ref_status_ok = False
                         del new_refs[ref]
 
             if new_refs is None:
                 proto.write_pkt_line(None)
                 return SendPackResult(old_refs, agent=agent, ref_status={})
 
             if len(new_refs) == 0 and orig_new_refs:
                 # NOOP - Original new refs filtered out by policy
                 proto.write_pkt_line(None)
                 if report_status_parser is not None:
                     ref_status = dict(report_status_parser.check())
                 else:
                     ref_status = None
                 return SendPackResult(old_refs, agent=agent, ref_status=ref_status)
 
             (have, want) = self._handle_receive_pack_head(
                 proto, negotiated_capabilities, old_refs, new_refs
             )
 
             pack_data_count, pack_data = generate_pack_data(
                 have,
                 want,
                 ofs_delta=(CAPABILITY_OFS_DELTA in negotiated_capabilities),
             )
 
             if self._should_send_pack(new_refs):
                 write_pack_data(proto.write_file(), pack_data_count, pack_data)
 
             ref_status = self._handle_receive_pack_tail(
                 proto, negotiated_capabilities, progress
             )
             return SendPackResult(new_refs, agent=agent, ref_status=ref_status)
 
     def fetch_pack(
         self,
         path,
         determine_wants,
         graph_walker,
         pack_data,
         progress=None,
         depth=None,
     ):
         """Retrieve a pack from a git smart server.
 
         Args:
           path: Remote path to fetch from
           determine_wants: Function determine what refs
             to fetch. Receives dictionary of name->sha, should return
             list of shas to fetch.
           graph_walker: Object with next() and ack().
           pack_data: Callback called for each bit of data in the pack
           progress: Callback for progress reports (strings)
           depth: Shallow fetch depth
 
         Returns:
           FetchPackResult object
 
         """
         proto, can_read, stderr = self._connect(b"upload-pack", path)
         with proto:
             try:
                 refs, server_capabilities = read_pkt_refs(proto)
             except HangupException:
                 raise _remote_error_from_stderr(stderr)
             (
                 negotiated_capabilities,
                 symrefs,
                 agent,
             ) = self._negotiate_upload_pack_capabilities(server_capabilities)
 
             if refs is None:
                 proto.write_pkt_line(None)
                 return FetchPackResult(refs, symrefs, agent)
 
             try:
                 if depth is not None:
                     wants = determine_wants(refs, depth=depth)
                 else:
                     wants = determine_wants(refs)
             except BaseException:
                 proto.write_pkt_line(None)
                 raise
             if wants is not None:
                 wants = [cid for cid in wants if cid != ZERO_SHA]
             if not wants:
                 proto.write_pkt_line(None)
                 return FetchPackResult(refs, symrefs, agent)
             (new_shallow, new_unshallow) = self._handle_upload_pack_head(
                 proto,
                 negotiated_capabilities,
                 graph_walker,
                 wants,
                 can_read,
                 depth=depth,
             )
             self._handle_upload_pack_tail(
                 proto,
                 negotiated_capabilities,
                 graph_walker,
                 pack_data,
                 progress,
             )
             return FetchPackResult(refs, symrefs, agent, new_shallow, new_unshallow)
 
     def get_refs(self, path):
         """Retrieve the current refs from a git smart server."""
         # stock `git ls-remote` uses upload-pack
         proto, _, stderr = self._connect(b"upload-pack", path)
         with proto:
             try:
                 refs, _ = read_pkt_refs(proto)
             except HangupException:
                 raise _remote_error_from_stderr(stderr)
             proto.write_pkt_line(None)
             return refs
 
     def archive(
         self,
         path,
         committish,
         write_data,
         progress=None,
         write_error=None,
         format=None,
         subdirs=None,
         prefix=None,
     ):
         proto, can_read, stderr = self._connect(b"upload-archive", path)
         with proto:
             if format is not None:
                 proto.write_pkt_line(b"argument --format=" + format)
             proto.write_pkt_line(b"argument " + committish)
             if subdirs is not None:
                 for subdir in subdirs:
                     proto.write_pkt_line(b"argument " + subdir)
             if prefix is not None:
                 proto.write_pkt_line(b"argument --prefix=" + prefix)
             proto.write_pkt_line(None)
             try:
                 pkt = proto.read_pkt_line()
             except HangupException:
                 raise _remote_error_from_stderr(stderr)
             if pkt == b"NACK\n" or pkt == b"NACK":
                 return
             elif pkt == b"ACK\n" or pkt == b"ACK":
                 pass
             elif pkt.startswith(b"ERR "):
                 raise GitProtocolError(pkt[4:].rstrip(b"\n").decode("utf-8", "replace"))
             else:
                 raise AssertionError("invalid response %r" % pkt)
             ret = proto.read_pkt_line()
             if ret is not None:
                 raise AssertionError("expected pkt tail")
             self._read_side_band64k_data(
                 proto,
                 {
                     SIDE_BAND_CHANNEL_DATA: write_data,
                     SIDE_BAND_CHANNEL_PROGRESS: progress,
                     SIDE_BAND_CHANNEL_FATAL: write_error,
                 },
             )
 
 
 class TCPGitClient(TraditionalGitClient):
     """A Git Client that works over TCP directly (i.e. git://)."""
 
     def __init__(self, host, port=None, **kwargs):
         if port is None:
             port = TCP_GIT_PORT
         self._host = host
         self._port = port
         super(TCPGitClient, self).__init__(**kwargs)
 
     @classmethod
     def from_parsedurl(cls, parsedurl, **kwargs):
         return cls(parsedurl.hostname, port=parsedurl.port, **kwargs)
 
     def get_url(self, path):
         netloc = self._host
         if self._port is not None and self._port != TCP_GIT_PORT:
             netloc += ":%d" % self._port
         return urlunsplit(("git", netloc, path, "", ""))
 
     def _connect(self, cmd, path):
         if not isinstance(cmd, bytes):
             raise TypeError(cmd)
         if not isinstance(path, bytes):
             path = path.encode(self._remote_path_encoding)
         sockaddrs = socket.getaddrinfo(
             self._host, self._port, socket.AF_UNSPEC, socket.SOCK_STREAM
         )
         s = None
         err = socket.error("no address found for %s" % self._host)
         for (family, socktype, proto, canonname, sockaddr) in sockaddrs:
             s = socket.socket(family, socktype, proto)
             s.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
             try:
                 s.connect(sockaddr)
                 break
             except socket.error as e:
                 err = e
                 if s is not None:
                     s.close()
                 s = None
         if s is None:
             raise err
         # -1 means system default buffering
         rfile = s.makefile("rb", -1)
         # 0 means unbuffered
         wfile = s.makefile("wb", 0)
 
         def close():
             rfile.close()
             wfile.close()
             s.close()
 
         proto = Protocol(
             rfile.read,
             wfile.write,
             close,
             report_activity=self._report_activity,
         )
         if path.startswith(b"/~"):
             path = path[1:]
         # TODO(jelmer): Alternative to ascii?
         proto.send_cmd(b"git-" + cmd, path, b"host=" + self._host.encode("ascii"))
         return proto, lambda: _fileno_can_read(s), None
 
 
 class SubprocessWrapper(object):
     """A socket-like object that talks to a subprocess via pipes."""
 
     def __init__(self, proc):
         self.proc = proc
         self.read = BufferedReader(proc.stdout).read
         self.write = proc.stdin.write
 
     @property
     def stderr(self):
         return self.proc.stderr
 
     def can_read(self):
         if sys.platform == "win32":
             from msvcrt import get_osfhandle
 
             handle = get_osfhandle(self.proc.stdout.fileno())
             return _win32_peek_avail(handle) != 0
         else:
             return _fileno_can_read(self.proc.stdout.fileno())
 
     def close(self):
         self.proc.stdin.close()
         self.proc.stdout.close()
         if self.proc.stderr:
             self.proc.stderr.close()
         self.proc.wait()
 
 
 def find_git_command():
     """Find command to run for system Git (usually C Git)."""
     if sys.platform == "win32":  # support .exe, .bat and .cmd
         try:  # to avoid overhead
             import win32api
         except ImportError:  # run through cmd.exe with some overhead
             return ["cmd", "/c", "git"]
         else:
             status, git = win32api.FindExecutable("git")
             return [git]
     else:
         return ["git"]
 
 
 class SubprocessGitClient(TraditionalGitClient):
     """Git client that talks to a server using a subprocess."""
 
     @classmethod
     def from_parsedurl(cls, parsedurl, **kwargs):
         return cls(**kwargs)
 
     git_command = None
 
     def _connect(self, service, path):
         if not isinstance(service, bytes):
             raise TypeError(service)
         if isinstance(path, bytes):
             path = path.decode(self._remote_path_encoding)
         if self.git_command is None:
             git_command = find_git_command()
         argv = git_command + [service.decode("ascii"), path]
         p = subprocess.Popen(
             argv,
             bufsize=0,
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
         pw = SubprocessWrapper(p)
         return (
             Protocol(
                 pw.read,
                 pw.write,
                 pw.close,
                 report_activity=self._report_activity,
             ),
             pw.can_read,
             p.stderr,
         )
 
 
 class LocalGitClient(GitClient):
     """Git Client that just uses a local Repo."""
 
     def __init__(self, thin_packs=True, report_activity=None, config=None):
         """Create a new LocalGitClient instance.
 
         Args:
           thin_packs: Whether or not thin packs should be retrieved
           report_activity: Optional callback for reporting transport
             activity.
         """
         self._report_activity = report_activity
         # Ignore the thin_packs argument
 
     def get_url(self, path):
         return urlunsplit(("file", "", path, "", ""))
 
     @classmethod
     def from_parsedurl(cls, parsedurl, **kwargs):
         return cls(**kwargs)
 
     @classmethod
     def _open_repo(cls, path):
         from dulwich.repo import Repo
 
         if not isinstance(path, str):
             path = os.fsdecode(path)
         return closing(Repo(path))
 
     def send_pack(self, path, update_refs, generate_pack_data, progress=None):
         """Upload a pack to a remote repository.
 
         Args:
           path: Repository path (as bytestring)
           update_refs: Function to determine changes to remote refs.
             Receive dict with existing remote refs, returns dict with
             changed refs (name -> sha, where sha=ZERO_SHA for deletions)
             with number of items and pack data to upload.
           progress: Optional progress function
 
         Returns:
           SendPackResult
 
         Raises:
           SendPackError: if server rejects the pack data
 
         """
         if not progress:
 
             def progress(x):
                 pass
 
         with self._open_repo(path) as target:
             old_refs = target.get_refs()
             new_refs = update_refs(dict(old_refs))
 
             have = [sha1 for sha1 in old_refs.values() if sha1 != ZERO_SHA]
             want = []
             for refname, new_sha1 in new_refs.items():
                 if (
                     new_sha1 not in have
                     and new_sha1 not in want
                     and new_sha1 != ZERO_SHA
                 ):
                     want.append(new_sha1)
 
             if not want and set(new_refs.items()).issubset(set(old_refs.items())):
                 return SendPackResult(new_refs, ref_status={})
 
             target.object_store.add_pack_data(
                 *generate_pack_data(have, want, ofs_delta=True)
             )
 
             ref_status = {}
 
             for refname, new_sha1 in new_refs.items():
                 old_sha1 = old_refs.get(refname, ZERO_SHA)
                 if new_sha1 != ZERO_SHA:
                     if not target.refs.set_if_equals(refname, old_sha1, new_sha1):
                         msg = "unable to set %s to %s" % (refname, new_sha1)
                         progress(msg)
                         ref_status[refname] = msg
                 else:
                     if not target.refs.remove_if_equals(refname, old_sha1):
                         progress("unable to remove %s" % refname)
                         ref_status[refname] = "unable to remove"
 
         return SendPackResult(new_refs, ref_status=ref_status)
 
     def fetch(self, path, target, determine_wants=None, progress=None, depth=None):
         """Fetch into a target repository.
 
         Args:
           path: Path to fetch from (as bytestring)
           target: Target repository to fetch into
           determine_wants: Optional function determine what refs
             to fetch. Receives dictionary of name->sha, should return
             list of shas to fetch. Defaults to all shas.
           progress: Optional progress function
           depth: Shallow fetch depth
 
         Returns:
           FetchPackResult object
 
         """
         with self._open_repo(path) as r:
             refs = r.fetch(
                 target,
                 determine_wants=determine_wants,
                 progress=progress,
                 depth=depth,
             )
             return FetchPackResult(refs, r.refs.get_symrefs(), agent_string())
 
     def fetch_pack(
         self,
         path,
         determine_wants,
         graph_walker,
         pack_data,
         progress=None,
         depth=None,
     ):
         """Retrieve a pack from a git smart server.
 
         Args:
           path: Remote path to fetch from
           determine_wants: Function determine what refs
             to fetch. Receives dictionary of name->sha, should return
             list of shas to fetch.
           graph_walker: Object with next() and ack().
           pack_data: Callback called for each bit of data in the pack
           progress: Callback for progress reports (strings)
           depth: Shallow fetch depth
 
         Returns:
           FetchPackResult object
 
         """
         with self._open_repo(path) as r:
             objects_iter = r.fetch_objects(
                 determine_wants, graph_walker, progress=progress, depth=depth
             )
             symrefs = r.refs.get_symrefs()
             agent = agent_string()
 
             # Did the process short-circuit (e.g. in a stateless RPC call)?
             # Note that the client still expects a 0-object pack in most cases.
             if objects_iter is None:
                 return FetchPackResult(None, symrefs, agent)
             protocol = ProtocolFile(None, pack_data)
             write_pack_objects(protocol, objects_iter)
             return FetchPackResult(r.get_refs(), symrefs, agent)
 
     def get_refs(self, path):
         """Retrieve the current refs from a git smart server."""
 
         with self._open_repo(path) as target:
             return target.get_refs()
 
 
 # What Git client to use for local access
 default_local_git_client_cls = LocalGitClient
 
 
 class SSHVendor(object):
     """A client side SSH implementation."""
 
     def connect_ssh(
         self,
         host,
         command,
         username=None,
         port=None,
         password=None,
         key_filename=None,
     ):
         # This function was deprecated in 0.9.1
         import warnings
 
         warnings.warn(
             "SSHVendor.connect_ssh has been renamed to SSHVendor.run_command",
             DeprecationWarning,
         )
         return self.run_command(
             host,
             command,
             username=username,
             port=port,
             password=password,
             key_filename=key_filename,
         )
 
     def run_command(
         self,
         host,
         command,
         username=None,
         port=None,
         password=None,
         key_filename=None,
     ):
         """Connect to an SSH server.
 
         Run a command remotely and return a file-like object for interaction
         with the remote command.
 
         Args:
           host: Host name
           command: Command to run (as argv array)
           username: Optional ame of user to log in as
           port: Optional SSH port to use
           password: Optional ssh password for login or private key
           key_filename: Optional path to private keyfile
 
         Returns:
 
         """
         raise NotImplementedError(self.run_command)
 
 
 class StrangeHostname(Exception):
     """Refusing to connect to strange SSH hostname."""
 
     def __init__(self, hostname):
         super(StrangeHostname, self).__init__(hostname)
 
 
 class SubprocessSSHVendor(SSHVendor):
     """SSH vendor that shells out to the local 'ssh' command."""
 
     def run_command(
         self,
         host,
         command,
         username=None,
         port=None,
         password=None,
         key_filename=None,
     ):
 
         if password is not None:
             raise NotImplementedError(
                 "Setting password not supported by SubprocessSSHVendor."
             )
 
         args = ["ssh", "-x"]
 
         if port:
             args.extend(["-p", str(port)])
 
         if key_filename:
             args.extend(["-i", str(key_filename)])
 
         if username:
             host = "%s@%s" % (username, host)
         if host.startswith("-"):
             raise StrangeHostname(hostname=host)
         args.append(host)
 
         proc = subprocess.Popen(
             args + [command],
             bufsize=0,
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
         return SubprocessWrapper(proc)
 
 
 class PLinkSSHVendor(SSHVendor):
     """SSH vendor that shells out to the local 'plink' command."""
 
     def run_command(
         self,
         host,
         command,
         username=None,
         port=None,
         password=None,
         key_filename=None,
     ):
 
         if sys.platform == "win32":
             args = ["plink.exe", "-ssh"]
         else:
             args = ["plink", "-ssh"]
 
         if password is not None:
             import warnings
 
             warnings.warn(
                 "Invoking PLink with a password exposes the password in the "
                 "process list."
             )
             args.extend(["-pw", str(password)])
 
         if port:
             args.extend(["-P", str(port)])
 
         if key_filename:
             args.extend(["-i", str(key_filename)])
 
         if username:
             host = "%s@%s" % (username, host)
         if host.startswith("-"):
             raise StrangeHostname(hostname=host)
         args.append(host)
 
         proc = subprocess.Popen(
             args + [command],
             bufsize=0,
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
         return SubprocessWrapper(proc)
 
 
 def ParamikoSSHVendor(**kwargs):
     import warnings
 
     warnings.warn(
         "ParamikoSSHVendor has been moved to dulwich.contrib.paramiko_vendor.",
         DeprecationWarning,
     )
     from dulwich.contrib.paramiko_vendor import ParamikoSSHVendor
 
     return ParamikoSSHVendor(**kwargs)
 
 
 # Can be overridden by users
 get_ssh_vendor = SubprocessSSHVendor
 
 
 class SSHGitClient(TraditionalGitClient):
     def __init__(
         self,
         host,
         port=None,
         username=None,
         vendor=None,
         config=None,
         password=None,
         key_filename=None,
         **kwargs
     ):
         self.host = host
         self.port = port
         self.username = username
         self.password = password
         self.key_filename = key_filename
         super(SSHGitClient, self).__init__(**kwargs)
         self.alternative_paths = {}
         if vendor is not None:
             self.ssh_vendor = vendor
         else:
             self.ssh_vendor = get_ssh_vendor()
 
     def get_url(self, path):
         netloc = self.host
         if self.port is not None:
             netloc += ":%d" % self.port
 
         if self.username is not None:
             netloc = urlquote(self.username, "@/:") + "@" + netloc
 
         return urlunsplit(("ssh", netloc, path, "", ""))
 
     @classmethod
     def from_parsedurl(cls, parsedurl, **kwargs):
         return cls(
             host=parsedurl.hostname,
             port=parsedurl.port,
             username=parsedurl.username,
             **kwargs
         )
 
     def _get_cmd_path(self, cmd):
         cmd = self.alternative_paths.get(cmd, b"git-" + cmd)
         assert isinstance(cmd, bytes)
         return cmd
 
     def _connect(self, cmd, path):
         if not isinstance(cmd, bytes):
             raise TypeError(cmd)
         if isinstance(path, bytes):
             path = path.decode(self._remote_path_encoding)
         if path.startswith("/~"):
             path = path[1:]
         argv = (
             self._get_cmd_path(cmd).decode(self._remote_path_encoding)
             + " '"
             + path
             + "'"
         )
         kwargs = {}
         if self.password is not None:
             kwargs["password"] = self.password
         if self.key_filename is not None:
             kwargs["key_filename"] = self.key_filename
         con = self.ssh_vendor.run_command(
             self.host, argv, port=self.port, username=self.username, **kwargs
         )
         return (
             Protocol(
                 con.read,
                 con.write,
                 con.close,
                 report_activity=self._report_activity,
             ),
             con.can_read,
             getattr(con, "stderr", None),
         )
 
 
 def default_user_agent_string():
     # Start user agent with "git/", because GitHub requires this. :-( See
     # https://github.com/jelmer/dulwich/issues/562 for details.
     return "git/dulwich/%s" % ".".join([str(x) for x in dulwich.__version__])
 
 
 def default_urllib3_manager(   # noqa: C901
     config, pool_manager_cls=None, proxy_manager_cls=None, **override_kwargs
 ):
     """Return `urllib3` connection pool manager.
 
     Honour detected proxy configurations.
 
     Args:
       config: dulwich.config.ConfigDict` instance with Git configuration.
       kwargs: Additional arguments for urllib3.ProxyManager
 
     Returns:
       `pool_manager_cls` (defaults to `urllib3.ProxyManager`) instance for
       proxy configurations, `proxy_manager_cls` (defaults to
       `urllib3.PoolManager`) instance otherwise.
 
     """
     proxy_server = user_agent = None
     ca_certs = ssl_verify = None
 
     if proxy_server is None:
         for proxyname in ("https_proxy", "http_proxy", "all_proxy"):
             proxy_server = os.environ.get(proxyname)
             if proxy_server is not None:
                 break
 
     if config is not None:
         if proxy_server is None:
             try:
                 proxy_server = config.get(b"http", b"proxy")
             except KeyError:
                 pass
         try:
             user_agent = config.get(b"http", b"useragent")
         except KeyError:
             pass
 
         # TODO(jelmer): Support per-host settings
         try:
             ssl_verify = config.get_boolean(b"http", b"sslVerify")
         except KeyError:
             ssl_verify = True
 
         try:
             ca_certs = config.get(b"http", b"sslCAInfo")
         except KeyError:
             ca_certs = None
 
     if user_agent is None:
         user_agent = default_user_agent_string()
 
     headers = {"User-agent": user_agent}
 
     kwargs = {}
     if ssl_verify is True:
         kwargs["cert_reqs"] = "CERT_REQUIRED"
     elif ssl_verify is False:
         kwargs["cert_reqs"] = "CERT_NONE"
     else:
         # Default to SSL verification
         kwargs["cert_reqs"] = "CERT_REQUIRED"
 
     if ca_certs is not None:
         kwargs["ca_certs"] = ca_certs
     kwargs.update(override_kwargs)
 
     # Try really hard to find a SSL certificate path
     if "ca_certs" not in kwargs and kwargs.get("cert_reqs") != "CERT_NONE":
         try:
             import certifi
         except ImportError:
             pass
         else:
             kwargs["ca_certs"] = certifi.where()
 
     import urllib3
 
     if proxy_server is not None:
         if proxy_manager_cls is None:
             proxy_manager_cls = urllib3.ProxyManager
         if not isinstance(proxy_server, str):
             proxy_server = proxy_server.decode()
         manager = proxy_manager_cls(proxy_server, headers=headers, **kwargs)
     else:
         if pool_manager_cls is None:
             pool_manager_cls = urllib3.PoolManager
         manager = pool_manager_cls(headers=headers, **kwargs)
 
     return manager
 
 
-class HttpGitClient(GitClient):
-    def __init__(
-        self,
-        base_url,
-        dumb=None,
-        pool_manager=None,
-        config=None,
-        username=None,
-        password=None,
-        **kwargs
-    ):
-        self._base_url = base_url.rstrip("/") + "/"
-        self._username = username
-        self._password = password
-        self.dumb = dumb
+class AbstractHttpGitClient(GitClient):
+    """Abstract base class for HTTP Git Clients.
 
-        if pool_manager is None:
-            self.pool_manager = default_urllib3_manager(config)
-        else:
-            self.pool_manager = pool_manager
-
-        if username is not None:
-            # No escaping needed: ":" is not allowed in username:
-            # https://tools.ietf.org/html/rfc2617#section-2
-            credentials = "%s:%s" % (username, password)
-            import urllib3.util
+    This is agonistic of the actual HTTP implementation.
 
-            basic_auth = urllib3.util.make_headers(basic_auth=credentials)
-            self.pool_manager.headers.update(basic_auth)
+    Subclasses should provide an implementation of the
+    _http_request method.
+    """
 
+    def __init__(self, base_url, dumb=False, **kwargs):
+        self._base_url = base_url.rstrip("/") + "/"
+        self.dumb = dumb
         GitClient.__init__(self, **kwargs)
 
-    def get_url(self, path):
-        return self._get_url(path).rstrip("/")
-
-    @classmethod
-    def from_parsedurl(cls, parsedurl, **kwargs):
-        password = parsedurl.password
-        if password is not None:
-            kwargs["password"] = urlunquote(password)
-        username = parsedurl.username
-        if username is not None:
-            kwargs["username"] = urlunquote(username)
-        netloc = parsedurl.hostname
-        if parsedurl.port:
-            netloc = "%s:%s" % (netloc, parsedurl.port)
-        if parsedurl.username:
-            netloc = "%s@%s" % (parsedurl.username, netloc)
-        parsedurl = parsedurl._replace(netloc=netloc)
-        return cls(urlunparse(parsedurl), **kwargs)
-
-    def __repr__(self):
-        return "%s(%r, dumb=%r)" % (
-            type(self).__name__,
-            self._base_url,
-            self.dumb,
-        )
-
-    def _get_url(self, path):
-        if not isinstance(path, str):
-            # urllib3.util.url._encode_invalid_chars() converts the path back
-            # to bytes using the utf-8 codec.
-            path = path.decode("utf-8")
-        return urljoin(self._base_url, path).rstrip("/") + "/"
-
     def _http_request(self, url, headers=None, data=None, allow_compression=False):
         """Perform HTTP request.
 
         Args:
           url: Request URL.
           headers: Optional custom headers to override defaults.
           data: Request data.
           allow_compression: Allow GZipped communication.
 
         Returns:
           Tuple (`response`, `read`), where response is an `urllib3`
           response object with additional `content_type` and
           `redirect_location` properties, and `read` is a consumable read
           method for the response data.
 
         """
-        req_headers = self.pool_manager.headers.copy()
-        if headers is not None:
-            req_headers.update(headers)
-        req_headers["Pragma"] = "no-cache"
-        if allow_compression:
-            req_headers["Accept-Encoding"] = "gzip"
-        else:
-            req_headers["Accept-Encoding"] = "identity"
 
-        if data is None:
-            resp = self.pool_manager.request("GET", url, headers=req_headers)
-        else:
-            resp = self.pool_manager.request(
-                "POST", url, headers=req_headers, body=data
-            )
-
-        if resp.status == 404:
-            raise NotGitRepository()
-        if resp.status == 401:
-            raise HTTPUnauthorized(resp.getheader("WWW-Authenticate"), url)
-        if resp.status == 407:
-            raise HTTPProxyUnauthorized(resp.getheader("Proxy-Authenticate"), url)
-        if resp.status != 200:
-            raise GitProtocolError(
-                "unexpected http resp %d for %s" % (resp.status, url)
-            )
-
-        # TODO: Optimization available by adding `preload_content=False` to the
-        # request and just passing the `read` method on instead of going via
-        # `BytesIO`, if we can guarantee that the entire response is consumed
-        # before issuing the next to still allow for connection reuse from the
-        # pool.
-        read = BytesIO(resp.data).read
-
-        resp.content_type = resp.getheader("Content-Type")
-        # Check if geturl() is available (urllib3 version >= 1.23)
-        try:
-            resp_url = resp.geturl()
-        except AttributeError:
-            # get_redirect_location() is available for urllib3 >= 1.1
-            resp.redirect_location = resp.get_redirect_location()
-        else:
-            resp.redirect_location = resp_url if resp_url != url else ""
-        return resp, read
+        raise NotImplementedError(self._http_request)
 
     def _discover_references(self, service, base_url):
         assert base_url[-1] == "/"
         tail = "info/refs"
         headers = {"Accept": "*/*"}
         if self.dumb is not True:
             tail += "?service=%s" % service.decode("ascii")
         url = urljoin(base_url, tail)
         resp, read = self._http_request(url, headers, allow_compression=True)
 
         if resp.redirect_location:
             # Something changed (redirect!), so let's update the base URL
             if not resp.redirect_location.endswith(tail):
                 raise GitProtocolError(
                     "Redirected from URL %s to URL %s without %s"
                     % (url, resp.redirect_location, tail)
                 )
             base_url = resp.redirect_location[: -len(tail)]
 
         try:
             self.dumb = not resp.content_type.startswith("application/x-git-")
             if not self.dumb:
                 proto = Protocol(read, None)
                 # The first line should mention the service
                 try:
                     [pkt] = list(proto.read_pkt_seq())
                 except ValueError:
                     raise GitProtocolError("unexpected number of packets received")
                 if pkt.rstrip(b"\n") != (b"# service=" + service):
                     raise GitProtocolError(
                         "unexpected first line %r from smart server" % pkt
                     )
                 return read_pkt_refs(proto) + (base_url,)
             else:
                 return read_info_refs(resp), set(), base_url
         finally:
             resp.close()
 
     def _smart_request(self, service, url, data):
+        """Send a 'smart' HTTP request.
+
+        This is a simple wrapper around _http_request that sets
+        a couple of extra headers.
+        """
         assert url[-1] == "/"
         url = urljoin(url, service)
         result_content_type = "application/x-%s-result" % service
         headers = {
             "Content-Type": "application/x-%s-request" % service,
             "Accept": result_content_type,
             "Content-Length": str(len(data)),
         }
         resp, read = self._http_request(url, headers, data)
         if resp.content_type != result_content_type:
             raise GitProtocolError(
                 "Invalid content-type from server: %s" % resp.content_type
             )
         return resp, read
 
     def send_pack(self, path, update_refs, generate_pack_data, progress=None):
         """Upload a pack to a remote repository.
 
         Args:
           path: Repository path (as bytestring)
           update_refs: Function to determine changes to remote refs.
             Receives dict with existing remote refs, returns dict with
             changed refs (name -> sha, where sha=ZERO_SHA for deletions)
           generate_pack_data: Function that can return a tuple
             with number of elements and pack data to upload.
           progress: Optional progress function
 
         Returns:
           SendPackResult
 
         Raises:
           SendPackError: if server rejects the pack data
 
         """
         url = self._get_url(path)
         old_refs, server_capabilities, url = self._discover_references(
             b"git-receive-pack", url
         )
         (
             negotiated_capabilities,
             agent,
         ) = self._negotiate_receive_pack_capabilities(server_capabilities)
         negotiated_capabilities.add(capability_agent())
 
         if CAPABILITY_REPORT_STATUS in negotiated_capabilities:
             self._report_status_parser = ReportStatusParser()
 
         new_refs = update_refs(dict(old_refs))
         if new_refs is None:
             # Determine wants function is aborting the push.
             return SendPackResult(old_refs, agent=agent, ref_status={})
         if set(new_refs.items()).issubset(set(old_refs.items())):
             return SendPackResult(new_refs, agent=agent, ref_status={})
         if self.dumb:
             raise NotImplementedError(self.fetch_pack)
         req_data = BytesIO()
         req_proto = Protocol(None, req_data.write)
         (have, want) = self._handle_receive_pack_head(
             req_proto, negotiated_capabilities, old_refs, new_refs
         )
         pack_data_count, pack_data = generate_pack_data(
             have,
             want,
             ofs_delta=(CAPABILITY_OFS_DELTA in negotiated_capabilities),
         )
         if self._should_send_pack(new_refs):
             write_pack_data(req_proto.write_file(), pack_data_count, pack_data)
         resp, read = self._smart_request(
             "git-receive-pack", url, data=req_data.getvalue()
         )
         try:
             resp_proto = Protocol(read, None)
             ref_status = self._handle_receive_pack_tail(
                 resp_proto, negotiated_capabilities, progress
             )
             return SendPackResult(new_refs, agent=agent, ref_status=ref_status)
         finally:
             resp.close()
 
     def fetch_pack(
         self,
         path,
         determine_wants,
         graph_walker,
         pack_data,
         progress=None,
         depth=None,
     ):
         """Retrieve a pack from a git smart server.
 
         Args:
           path: Path to fetch from
           determine_wants: Callback that returns list of commits to fetch
           graph_walker: Object with next() and ack().
           pack_data: Callback called for each bit of data in the pack
           progress: Callback for progress reports (strings)
           depth: Depth for request
 
         Returns:
           FetchPackResult object
 
         """
         url = self._get_url(path)
         refs, server_capabilities, url = self._discover_references(
             b"git-upload-pack", url
         )
         (
             negotiated_capabilities,
             symrefs,
             agent,
         ) = self._negotiate_upload_pack_capabilities(server_capabilities)
         if depth is not None:
             wants = determine_wants(refs, depth=depth)
         else:
             wants = determine_wants(refs)
         if wants is not None:
             wants = [cid for cid in wants if cid != ZERO_SHA]
         if not wants:
             return FetchPackResult(refs, symrefs, agent)
         if self.dumb:
             raise NotImplementedError(self.fetch_pack)
         req_data = BytesIO()
         req_proto = Protocol(None, req_data.write)
         (new_shallow, new_unshallow) = self._handle_upload_pack_head(
             req_proto,
             negotiated_capabilities,
             graph_walker,
             wants,
             can_read=None,
             depth=depth,
         )
         resp, read = self._smart_request(
             "git-upload-pack", url, data=req_data.getvalue()
         )
         try:
             resp_proto = Protocol(read, None)
             if new_shallow is None and new_unshallow is None:
                 (new_shallow, new_unshallow) = _read_shallow_updates(resp_proto)
             self._handle_upload_pack_tail(
                 resp_proto,
                 negotiated_capabilities,
                 graph_walker,
                 pack_data,
                 progress,
             )
             return FetchPackResult(refs, symrefs, agent, new_shallow, new_unshallow)
         finally:
             resp.close()
 
     def get_refs(self, path):
         """Retrieve the current refs from a git smart server."""
         url = self._get_url(path)
         refs, _, _ = self._discover_references(b"git-upload-pack", url)
         return refs
 
+    def get_url(self, path):
+        return self._get_url(path).rstrip("/")
+
+    def _get_url(self, path):
+        return urljoin(self._base_url, path).rstrip("/") + "/"
+
+    @classmethod
+    def from_parsedurl(cls, parsedurl, **kwargs):
+        password = parsedurl.password
+        if password is not None:
+            kwargs["password"] = urlunquote(password)
+        username = parsedurl.username
+        if username is not None:
+            kwargs["username"] = urlunquote(username)
+        netloc = parsedurl.hostname
+        if parsedurl.port:
+            netloc = "%s:%s" % (netloc, parsedurl.port)
+        if parsedurl.username:
+            netloc = "%s@%s" % (parsedurl.username, netloc)
+        parsedurl = parsedurl._replace(netloc=netloc)
+        return cls(urlunparse(parsedurl), **kwargs)
+
+    def __repr__(self):
+        return "%s(%r, dumb=%r)" % (
+            type(self).__name__,
+            self._base_url,
+            self.dumb,
+        )
+
+
+class Urllib3HttpGitClient(AbstractHttpGitClient):
+    def __init__(
+        self,
+        base_url,
+        dumb=None,
+        pool_manager=None,
+        config=None,
+        username=None,
+        password=None,
+        **kwargs
+    ):
+        self._username = username
+        self._password = password
+
+        if pool_manager is None:
+            self.pool_manager = default_urllib3_manager(config)
+        else:
+            self.pool_manager = pool_manager
+
+        if username is not None:
+            # No escaping needed: ":" is not allowed in username:
+            # https://tools.ietf.org/html/rfc2617#section-2
+            credentials = "%s:%s" % (username, password)
+            import urllib3.util
+
+            basic_auth = urllib3.util.make_headers(basic_auth=credentials)
+            self.pool_manager.headers.update(basic_auth)
+
+        super(Urllib3HttpGitClient, self).__init__(
+            base_url=base_url, dumb=dumb, **kwargs)
+
+    def _get_url(self, path):
+        if not isinstance(path, str):
+            # urllib3.util.url._encode_invalid_chars() converts the path back
+            # to bytes using the utf-8 codec.
+            path = path.decode("utf-8")
+        return urljoin(self._base_url, path).rstrip("/") + "/"
+
+    def _http_request(self, url, headers=None, data=None, allow_compression=False):
+        req_headers = self.pool_manager.headers.copy()
+        if headers is not None:
+            req_headers.update(headers)
+        req_headers["Pragma"] = "no-cache"
+        if allow_compression:
+            req_headers["Accept-Encoding"] = "gzip"
+        else:
+            req_headers["Accept-Encoding"] = "identity"
+
+        if data is None:
+            resp = self.pool_manager.request("GET", url, headers=req_headers)
+        else:
+            resp = self.pool_manager.request(
+                "POST", url, headers=req_headers, body=data
+            )
+
+        if resp.status == 404:
+            raise NotGitRepository()
+        if resp.status == 401:
+            raise HTTPUnauthorized(resp.getheader("WWW-Authenticate"), url)
+        if resp.status == 407:
+            raise HTTPProxyUnauthorized(resp.getheader("Proxy-Authenticate"), url)
+        if resp.status != 200:
+            raise GitProtocolError(
+                "unexpected http resp %d for %s" % (resp.status, url)
+            )
+
+        # TODO: Optimization available by adding `preload_content=False` to the
+        # request and just passing the `read` method on instead of going via
+        # `BytesIO`, if we can guarantee that the entire response is consumed
+        # before issuing the next to still allow for connection reuse from the
+        # pool.
+        read = BytesIO(resp.data).read
+
+        resp.content_type = resp.getheader("Content-Type")
+        # Check if geturl() is available (urllib3 version >= 1.23)
+        try:
+            resp_url = resp.geturl()
+        except AttributeError:
+            # get_redirect_location() is available for urllib3 >= 1.1
+            resp.redirect_location = resp.get_redirect_location()
+        else:
+            resp.redirect_location = resp_url if resp_url != url else ""
+        return resp, read
+
+
+HttpGitClient = Urllib3HttpGitClient
+
 
 def get_transport_and_path_from_url(url, config=None, **kwargs):
     """Obtain a git client from a URL.
 
     Args:
       url: URL to open (a unicode string)
       config: Optional config object
       thin_packs: Whether or not thin packs should be retrieved
       report_activity: Optional callback for reporting transport
         activity.
 
     Returns:
       Tuple with client instance and relative path.
 
     """
     parsed = urlparse(url)
     if parsed.scheme == "git":
         return (TCPGitClient.from_parsedurl(parsed, **kwargs), parsed.path)
     elif parsed.scheme in ("git+ssh", "ssh"):
         return SSHGitClient.from_parsedurl(parsed, **kwargs), parsed.path
     elif parsed.scheme in ("http", "https"):
         return (
             HttpGitClient.from_parsedurl(parsed, config=config, **kwargs),
             parsed.path,
         )
     elif parsed.scheme == "file":
         return (
             default_local_git_client_cls.from_parsedurl(parsed, **kwargs),
             parsed.path,
         )
 
     raise ValueError("unknown scheme '%s'" % parsed.scheme)
 
 
 def parse_rsync_url(location):
     """Parse a rsync-style URL."""
     if ":" in location and "@" not in location:
         # SSH with no user@, zero or one leading slash.
         (host, path) = location.split(":", 1)
         user = None
     elif ":" in location:
         # SSH with user@host:foo.
         user_host, path = location.split(":", 1)
         if "@" in user_host:
             user, host = user_host.rsplit("@", 1)
         else:
             user = None
             host = user_host
     else:
         raise ValueError("not a valid rsync-style URL")
     return (user, host, path)
 
 
 def get_transport_and_path(location, **kwargs):
     """Obtain a git client from a URL.
 
     Args:
       location: URL or path (a string)
       config: Optional config object
       thin_packs: Whether or not thin packs should be retrieved
       report_activity: Optional callback for reporting transport
         activity.
 
     Returns:
       Tuple with client instance and relative path.
 
     """
     # First, try to parse it as a URL
     try:
         return get_transport_and_path_from_url(location, **kwargs)
     except ValueError:
         pass
 
     if sys.platform == "win32" and location[0].isalpha() and location[1:3] == ":\\":
         # Windows local path
         return default_local_git_client_cls(**kwargs), location
 
     try:
         (username, hostname, path) = parse_rsync_url(location)
     except ValueError:
         # Otherwise, assume it's a local path.
         return default_local_git_client_cls(**kwargs), location
     else:
         return SSHGitClient(hostname, username=username, **kwargs), path
 
 
 DEFAULT_GIT_CREDENTIALS_PATHS = [
     os.path.expanduser("~/.git-credentials"),
     get_xdg_config_home_path("git", "credentials"),
 ]
 
 
 def get_credentials_from_store(
     scheme, hostname, username=None, fnames=DEFAULT_GIT_CREDENTIALS_PATHS
 ):
     for fname in fnames:
         try:
             with open(fname, "rb") as f:
                 for line in f:
                     parsed_line = urlparse(line.strip())
                     if (
                         parsed_line.scheme == scheme
                         and parsed_line.hostname == hostname
                         and (username is None or parsed_line.username == username)
                     ):
                         return parsed_line.username, parsed_line.password
         except FileNotFoundError:
             # If the file doesn't exist, try the next one.
             continue