I'm unable to confirm this patch helps matters.

While it applies cleanly, it doesn't seem to solve the problem.  bzr pull  still fails, but this time with:

bzr: ERROR: exceptions.TypeError: 'list' object is not callable

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/builtins.py", line 1243, in run
    local=local, show_base=show_base)
  File "/usr/lib/python2.7/dist-packages/bzrlib/decorators.py", line 218, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/workingtree.py", line 999, in pull
    local=local)
  File "/usr/lib/python2.7/dist-packages/bzrlib/branch.py", line 1111, in pull
    possible_transports=possible_transports, *args, **kwargs)
  File "/home/leo/.bazaar/plugins/git/branch.py", line 842, in pull
    _override_hook_target, _hook_master=master_branch)
  File "/home/leo/.bazaar/plugins/git/branch.py", line 778, in _basic_pull
    stop_revision, overwrite=overwrite)
  File "/home/leo/.bazaar/plugins/git/branch.py", line 752, in _update_revisions
    head, refs = self.fetch_objects(stop_revision, fetch_tags=None)
  File "/home/leo/.bazaar/plugins/git/branch.py", line 745, in fetch_objects
    determine_wants, self.source.mapping, limit=limit)
  File "/home/leo/.bazaar/plugins/git/fetch.py", line 714, in fetch_objects
    progress=lambda text: report_git_progress(pb, text))
  File "/home/leo/.bazaar/plugins/git/remote.py", line 461, in fetch_objects
    lambda x: os.write(fd, x), progress)
  File "/home/leo/.bazaar/plugins/git/remote.py", line 451, in fetch_pack
    pack_data, progress)
  File "/home/leo/.bazaar/plugins/git/remote.py", line 270, in fetch_pack
    graph_walker, pack_data, progress)
  File "/usr/lib/python2.7/dist-packages/dulwich/client.py", line 528, in fetch_pack
    graph_walker, wants, can_read)
  File "/usr/lib/python2.7/dist-packages/dulwich/client.py", line 355, in _handle_upload_pack_head
    have = next(graph_walker)
  File "/usr/lib/python2.7/dist-packages/dulwich/object_store.py", line 1104, in next
    ps = self.get_parents(ret)
TypeError: 'list' object is not callable

bzr 2.7.0dev1 on python 2.7.7 (Linux-3.14-1-amd64-x86_64-with-debian-jessie-
    sid)
arguments: ['/usr/bin/bzr', 'pull',
    '<email address hidden>:SocialFlowDev/SocialFlow-S3.git']
plugins: bash_completion[2.7.0dev1], bisect[1.1.0dev], bzrtools[2.6.0],
    changelog_merge[2.7.0dev1], git[0.6.12], grep[2.7.0dev1],
    launchpad[2.7.0dev1], netrc_credential_store[2.7.0dev1],
    news_merge[2.7.0dev1], po_merge[2.7.0dev1], rewrite[0.6.4dev],
    weave_fmt[2.7.0dev1]
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'en_GB.utf8'

Using

ii  python-dulwich   0.9.6-1       amd64         Python Git library