This error seems to be relative to parsing error of legacy object within the dulwich dependency.
To reproduce, use the following repository /srv/storage/space/mirrors/gitorious.org/mnt/repositories/sortix/sortix-gitorious-wiki.git:
```
repo = 'sortix-gitorious-wiki.git'
origin_url = 'http://foo/bar/git'
import logging
logging.basicConfig(level=logging.DEBUG)
from swh.loader.git.tasks import LoadDiskGitRepository
t = LoadDiskGitRepository()
t.run(origin_url=origin_url, directory=repo, date='2016-05-03T15:16:32+00:00')
```
output:
```
DEBUG:swh.scheduler.task.LoadDiskGitRepository:Creating git origin for http://foo/bar/sortix-gitorious-wiki.git
DEBUG:swh.scheduler.task.LoadDiskGitRepository:Done creating git origin for http://foo/bar/sortix-gitorious-wiki.git
Traceback (most recent call last):
File "./load-git-disk.py", line 20, in <module>
main()
File "/usr/lib/python3/dist-packages/click/core.py", line 716, in __call__
return self.main(*args, **kwargs)
File "/usr/lib/python3/dist-packages/click/core.py", line 696, in main
rv = self.invoke(ctx)
File "/usr/lib/python3/dist-packages/click/core.py", line 889, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/lib/python3/dist-packages/click/core.py", line 534, in invoke
return callback(*args, **kwargs)
File "./load-git-disk.py", line 17, in main
t.run(origin_url=origin_url, directory=repo, date='2016-05-03T15:16:32+00:00')
File "/home/tony/work/inria/repo/swh/swh-environment/swh-scheduler/swh/scheduler/task.py", line 35, in run
raise e from None
File "/home/tony/work/inria/repo/swh/swh-environment/swh-scheduler/swh/scheduler/task.py", line 32, in run
result = self.run_task(*args, **kwargs)
File "/home/tony/work/inria/repo/swh/swh-environment/swh-loader-git/swh/loader/git/tasks.py", line 39, in run_task
return loader.load(origin_url, directory, dateutil.parser.parse(date))
File "/home/tony/work/inria/repo/swh/swh-environment/swh-loader-git/swh/loader/git/base.py", line 422, in load
self.fetch_data()
File "/home/tony/work/inria/repo/swh/swh-environment/swh-loader-git/swh/loader/git/loader.py", line 48, in fetch_data
type_name = self.repo[oid].type_name
File "/usr/lib/python3/dist-packages/dulwich/repo.py", line 470, in __getitem__
return self.object_store[name]
File "/usr/lib/python3/dist-packages/dulwich/object_store.py", line 118, in __getitem__
type_num, uncomp = self.get_raw(sha)
File "/usr/lib/python3/dist-packages/dulwich/object_store.py", line 372, in get_raw
ret = self._get_loose_object(hexsha)
File "/usr/lib/python3/dist-packages/dulwich/object_store.py", line 521, in _get_loose_object
return ShaFile.from_path(path)
File "/usr/lib/python3/dist-packages/dulwich/objects.py", line 370, in from_path
return cls.from_file(f)
File "/usr/lib/python3/dist-packages/dulwich/objects.py", line 376, in from_file
obj = cls._parse_file(f)
File "/usr/lib/python3/dist-packages/dulwich/objects.py", line 346, in _parse_file
if cls._is_legacy_object(map):
File "/usr/lib/python3/dist-packages/dulwich/objects.py", line 338, in _is_legacy_object
b0 = ord(magic[0:1])
TypeError: ord() expected a character, but string of length 0 found
```