bzr branch fails with "sprout() got an unexpected keyword argument 'source_branch'"

bzr fails when trying to branch from: http://repo.spacepants.org/bzr/plugins/graft/

with the following traceback:
Format <RepositoryFormat6> for http://repo.spacepants.org/bzr/plugins/graft/.bzr/ is deprecated - please use 'bzr upgrade' to get better performance
bzr: ERROR: exceptions.TypeError: sprout() got an unexpected keyword argument 'source_branch'

Traceback (most recent call last):
  File "/home/asabil/Development/Resources/bzr/bzr/bzrlib/commands.py", line 893, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/home/asabil/Development/Resources/bzr/bzr/bzrlib/commands.py", line 839, in run_bzr
    ret = run(*run_argv)
  File "/home/asabil/Development/Resources/bzr/bzr/bzrlib/commands.py", line 539, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/asabil/Development/Resources/bzr/bzr/bzrlib/builtins.py", line 1043, in run
    source_branch=br_from)
TypeError: sprout() got an unexpected keyword argument 'source_branch'

bzr 1.12dev on python 2.5.2 (linux2)
arguments: ['/home/asabil/.local/bin/bzr', 'branch', 'http://repo.spacepants.org/bzr/plugins/graft/']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'
plugins:
  avahi /usr/lib/python2.5/site-packages/bzrlib/plugins/avahi [0.3dev]
  bisect /home/asabil/.bazaar/plugins/bisect [1.1.0.pre.0]
  builddeb /home/asabil/.bazaar/plugins/builddeb [2.1dev]
  bzrtools /home/asabil/.bazaar/plugins/bzrtools [1.11]
  dbus /usr/lib/python2.5/site-packages/bzrlib/plugins/dbus [unknown]
  fastimport /home/asabil/.bazaar/plugins/fastimport [unknown]
  git /home/asabil/.bazaar/plugins/git [unknown]
  gnomeds /home/asabil/.bazaar/plugins/gnomeds [unknown]
  gnulog /home/asabil/.bazaar/plugins/gnulog.py [unknown]
  gtk /home/asabil/.bazaar/plugins/gtk [0.96.0.dev.1]
  launchpad /home/asabil/Development/Resources/bzr/bzr/bzrlib/plugins/launchpad [unknown]
  netrc_credential_store /home/asabil/Development/Resources/bzr/bzr/bzrlib/plugins/netrc_credential_store [unknown]
  qbzr /home/asabil/.bazaar/plugins/qbzr [0.9.6dev]
  rebase /home/asabil/.bazaar/plugins/rebase [0.4.3dev]
  search /home/asabil/.bazaar/plugins/search [1.7dev]
  stats /usr/lib/python2.5/site-packages/bzrlib/plugins/stats [unknown]
  svn /home/asabil/.bazaar/plugins/svn [0.4.16]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.