Error running bzr-git with bzr 2.7.0 on OS X

Steps to reproduce:

git init sample
cd sample
touch test.txt
git add test.txt
git commit -m"some message"
bzr log

bzr: ERROR: exceptions.AttributeError: 'TransportRepo' object has no attribute 'ref'

Traceback (most recent call last):
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/commands.py", line 1138, in ignore_pipe
    result = func(*args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/builtins.py", line 2893, in run
    Logger(b, rqst).show(lf)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/log.py", line 382, in show
    self._show_body(lf)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/log.py", line 411, in _show_body
    for lr in generator.iter_log_revisions():
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/log.py", line 450, in iter_log_revisions
    revision_iterator = self._create_log_revision_iterator()
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/log.py", line 501, in _create_log_revision_iterator
    self.rqst.get('end_revision'))
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/log.py", line 1043, in _get_revision_limits
    branch_revno, branch_rev_id = branch.last_revision_info()
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/decorators.py", line 155, in read_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/branch.py", line 1049, in last_revision_info
    self._last_revision_info_cache = self._read_last_revision_info()
  File "/usr/local/share/bazaar/plugins/git/branch.py", line 563, in _read_last_revision_info
    last_revid = self.last_revision()
  File "/usr/local/Cellar/bazaar/2.7.0/libexec/bzrlib/decorators.py", line 155, in read_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/local/share/bazaar/plugins/git/branch.py", line 482, in last_revision
    if self.head is None:
  File "/usr/local/share/bazaar/plugins/git/branch.py", line 558, in _get_head
    return self.repository._git.ref(self.ref or "HEAD")
AttributeError: 'TransportRepo' object has no attribute 'ref'

bzr 2.7.0 on python 2.7.10 (Darwin-15.3.0-x86_64-i386-64bit)
arguments: ['/usr/local/Cellar/bazaar/2.7.0/libexec/bzr', 'log']
plugins: bash_completion[2.7.0], bisect[1.1.0dev], bzrtools[2.3.0],
    changelog_merge[2.7.0], difftools[0.91.0], explorer[1.3.0],
    extmerge[unknown], git[0.6.8], grep[2.7.0], launchpad[2.7.0],
    netrc_credential_store[2.7.0], news_merge[2.7.0], po_merge[2.7.0],
    qbzr[0.23.1], weave_fmt[2.7.0], xmloutput[0.8.8]
encoding: 'utf-8', fsenc: 'utf-8', lang: 'en_US.UTF-8'

*** Bazaar has encountered an internal error. This probably indicates a
    bug in Bazaar. You can help us fix it by filing a bug report at
        https://bugs.launchpad.net/bzr/+filebug
    including this traceback and a description of the problem.