AttributeError: 'BazaarObjectStore' object has no attribute 'get_graph_walker'

I am probably missing something obvious, but I cannot figure out a way to branch out of Git repository.

As far as I understand, this command should work:

  bzr branch git://github.com/jelmer/dulwich.git dulwich

Unfortunately, it produces the following error:

bzr: ERROR: exceptions.AttributeError: 'BazaarObjectStore' object has no attribute 'get_graph_walker'

Traceback (most recent call last):
  File "bzrlib\commands.pyo", line 930, in exception_to_return_code
  File "bzrlib\commands.pyo", line 1121, in run_bzr
  File "bzrlib\commands.pyo", line 673, in run_argv_aliases
  File "bzrlib\commands.pyo", line 697, in run
  File "bzrlib\cleanup.pyo", line 136, in run_simple
  File "bzrlib\cleanup.pyo", line 166, in _do_with_cleanups
  File "bzrlib\builtins.pyo", line 1507, in run
  File "C:/Program Files/Bazaar/plugins\git\dir.py", line 140, in sprout
  File "C:/Program Files/Bazaar/plugins\git\fetch.py", line 705, in fetch_objects
AttributeError: 'BazaarObjectStore' object has no attribute 'get_graph_walker'

bzr 2.6.0 on python 2.7.6 (Windows-7-6.1.7601-SP1)
arguments: ['C:\\Program Files\\Bazaar\\bzr.exe', 'branch',
    'git://github.com/jelmer/dulwich.git', 'dulwich']
plugins: bzrtools[2.5.0], changelog_merge[2.6.0], colo[0.4.0],
    explorer[1.3.0], fastimport[0.14.0dev], git[0.6.12], launchpad[2.6.0],
    loom[2.3.0dev], netrc_credential_store[2.6.0], news_merge[2.6.0],
    pipeline[1.4.0], qbzr[0.23.1], rewrite[0.6.4dev], svn[1.2.3],
    upload[1.2.0dev], xmloutput[0.8.9]
encoding: 'cp1251', fsenc: 'mbcs', lang: None

*** 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.

What should I do to fix this error?