hg plugin crashes

I was trying to import a hg repository using

> bzr init
> bzr pull ../mercurial-repo

and I got this error:
(full trace follows)

bzr: ERROR: exceptions.TypeError: fetch() got an unexpected keyword argument 'find_ghosts'

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 802, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 758, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 492, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 646, in run
    possible_transports=possible_transports)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree.py", line 1539, in pull
    possible_transports=possible_transports)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 1726, in pull
    run_hooks=run_hooks)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 1525, in pull
    self.update_revisions(source, stop_revision, overwrite=overwrite)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 1477, in update_revisions
    self.fetch(other, stop_revision)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 286, in fetch
    pb=nested_pb)
  File "/usr/lib/python2.5/site-packages/bzrlib/repository.py", line 873, in fetch
    return inter.fetch(revision_id=revision_id, pb=pb, find_ghosts=find_ghosts)
  File "/usr/lib/python2.5/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
TypeError: fetch() got an unexpected keyword argument 'find_ghosts'

bzr 1.0.0 on python 2.5.1.final.0 (linux2)
arguments: ['/usr/bin/bzr', 'pull', '../articulos-hg/']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'es_MX.UTF-8'
plugins:
  benchdisplay /home/nano/.bazaar/plugins/benchdisplay [unknown]
  bzr_git /home/nano/.bazaar/plugins/bzr_git [unknown]
  bzr_hg /home/nano/.bazaar/plugins/bzr_hg [unknown]
  bzr_hgimport /home/nano/.bazaar/plugins/bzr_hgimport [unknown]
  bzrtools /home/nano/.bazaar/plugins/bzrtools [1.1.0]
  diffstat /home/nano/.bazaar/plugins/diffstat [unknown]
  email /usr/lib/python2.5/site-packages/bzrlib/plugins/email [unknown]
  gtk /home/nano/.bazaar/plugins/gtk [0.94.0dev0]
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [unknown]
  multiparent /usr/lib/python2.5/site-packages/bzrlib/plugins/multiparent.pyc [unknown]
  stats /home/nano/.bazaar/plugins/stats [unknown]
*** 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.