bzr stats fails on OS X 10.11 with bzr 2.7.0

[Fred McCann]

Bazaar: 2.7.0
OS X: 10.11.3
Python: 2.7.11
bar-stats: 0.1.0

$> bzr stats
getting ancestry
bzr: ERROR: exceptions.AttributeError: 'CHKInventoryRepository' object has no attribute 'get_ancestry'

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/share/bazaar/plugins/stats/cmds.py", line 274, in run
    info = get_info(a_branch.repository, last_rev)
  File "/usr/local/share/bazaar/plugins/stats/cmds.py", line 169, in get_info
    ancestry = a_repo.get_ancestry(revision)[1:]
AttributeError: 'CHKInventoryRepository' object has no attribute 'get_ancestry'

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', 'stats']
plugins: bash_completion[2.7.0], bisect[1.1.0dev], bzrtools[2.3.0],
    changelog_merge[2.7.0], colo[0.4.0], difftools[0.91.0], explorer[1.3.0],
    externals[1.3.3], extmerge[unknown], 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], rewrite[0.6.3], stats[0.1.0], upload[1.1.0],
    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.

[Vincent Ladeuil (vila)]

Duplicate of #1040560