diff --git a/dulwich/objectspec.py b/dulwich/objectspec.py
index a2b6bc3d..205b07c0 100644
--- a/dulwich/objectspec.py
+++ b/dulwich/objectspec.py
@@ -1,161 +1,161 @@
 # objectspec.py -- Object specification
 # Copyright (C) 2014 Jelmer Vernooij <jelmer@samba.org>
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
 # as published by the Free Software Foundation; version 2
 # of the License or (at your option) a later version of the License.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 # MA  02110-1301, USA.
 
 """Object specification."""
 
 
 def to_bytes(text):
     if getattr(text, "encode", None) is not None:
         text = text.encode('ascii')
     return text
 
 
 def parse_object(repo, objectish):
     """Parse a string referring to an object.
 
     :param repo: A `Repo` object
     :param objectish: A string referring to an object
     :return: A git object
     :raise KeyError: If the object can not be found
     """
     objectish = to_bytes(objectish)
     return repo[objectish]
 
 
 def parse_ref(container, refspec):
     """Parse a string referring to a reference.
 
     :param container: A RefsContainer object
     :param refspec: A string referring to a ref
     :return: A ref
     :raise KeyError: If the ref can not be found
     """
     refspec = to_bytes(refspec)
     possible_refs = [
         refspec,
         b"refs/" + refspec,
         b"refs/tags/" + refspec,
         b"refs/heads/" + refspec,
         b"refs/remotes/" + refspec,
         b"refs/remotes/" + refspec + b"/HEAD"
     ]
     for ref in possible_refs:
         if ref in container:
             return ref
     else:
         raise KeyError(refspec)
 
 
 def parse_reftuple(lh_container, rh_container, refspec):
     """Parse a reftuple spec.
 
     :param lh_container: A RefsContainer object
     :param hh_container: A RefsContainer object
     :param refspec: A string
     :return: A tuple with left and right ref
     :raise KeyError: If one of the refs can not be found
     """
     if refspec.startswith(b"+"):
         force = True
         refspec = refspec[1:]
     else:
         force = False
     refspec = to_bytes(refspec)
     if b":" in refspec:
         (lh, rh) = refspec.split(b":")
     else:
         lh = rh = refspec
-    if rh == b"":
+    if lh == b"":
         lh = None
     else:
         lh = parse_ref(lh_container, lh)
     if rh == b"":
         rh = None
     else:
         try:
             rh = parse_ref(rh_container, rh)
         except KeyError:
             # TODO: check force?
             if not b"/" in rh:
                 rh = b"refs/heads/" + rh
     return (lh, rh, force)
 
 
 def parse_reftuples(lh_container, rh_container, refspecs):
     """Parse a list of reftuple specs to a list of reftuples.
 
     :param lh_container: A RefsContainer object
     :param hh_container: A RefsContainer object
     :param refspecs: A list of refspecs or a string
     :return: A list of refs
     :raise KeyError: If one of the refs can not be found
     """
     if not isinstance(refspecs, list):
         refspecs = [refspecs]
     ret = []
     # TODO: Support * in refspecs
     for refspec in refspecs:
         ret.append(parse_reftuple(lh_container, rh_container, refspec))
     return ret
 
 
 def parse_refs(container, refspecs):
     """Parse a list of refspecs to a list of refs.
 
     :param container: A RefsContainer object
     :param refspecs: A list of refspecs or a string
     :return: A list of refs
     :raise KeyError: If one of the refs can not be found
     """
     # TODO: Support * in refspecs
     if not isinstance(refspecs, list):
         refspecs = [refspecs]
     ret = []
     for refspec in refspecs:
         ret.append(parse_ref(container, refspec))
     return ret
 
 
 def parse_commit_range(repo, committishs):
     """Parse a string referring to a range of commits.
 
     :param repo: A `Repo` object
     :param committishs: A string referring to a range of commits.
     :return: An iterator over `Commit` objects
     :raise KeyError: When the reference commits can not be found
     :raise ValueError: If the range can not be parsed
     """
     committishs = to_bytes(committishs)
     # TODO(jelmer): Support more than a single commit..
     return iter([parse_commit(repo, committishs)])
 
 
 def parse_commit(repo, committish):
     """Parse a string referring to a single commit.
 
     :param repo: A` Repo` object
     :param commitish: A string referring to a single commit.
     :return: A Commit object
     :raise KeyError: When the reference commits can not be found
     :raise ValueError: If the range can not be parsed
     """
     committish = to_bytes(committish)
     return repo[committish] # For now..
 
 
 # TODO: parse_path_in_tree(), which handles e.g. v1.0:Documentation