gcommit simply does not execute returning an error

[Alexandre]

$ bzr gcommit
bzr: ERROR: exceptions.AssertionError: How did we get here?

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 893, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 839, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 539, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/gtk/__init__.py", line 393, in run
    dlg = CommitDialog(wt)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/gtk/commit.py", line 119, in __init__
    self.fill_in_data()
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/gtk/commit.py", line 133, in fill_in_data
    self._fill_in_files()
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/gtk/commit.py", line 191, in _fill_in_files
    ) in iter_changes_to_status(self._basis_tree, self._wt):
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/gtk/diff.py", line 695, in iter_changes_to_status
    assert False, "How did we get here?"
AssertionError: How did we get here?

bzr 1.9 on python 2.5.2 (linux2)
arguments: ['/usr/bin/bzr', 'gcommit']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'pt_BR.UTF-8'
plugins:
  avahi /usr/lib/python2.5/site-packages/bzrlib/plugins/avahi [0.3.0dev0]
  bzrtools /usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools [1.9.1]
  dbus /usr/lib/python2.5/site-packages/bzrlib/plugins/dbus [unknown]
  gtk /usr/lib/python2.5/site-packages/bzrlib/plugins/gtk [0.95.0]
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [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.

some times other like gdiff also doesn't work, but now I can't reproduce.