bzr: ERROR: exceptions.AssertionError:

Traceback (most recent call last):
  File "/usr/local/lib/python2.4/site-packages/bzrlib/commands.py", line 718, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/commands.py", line 679, in run_bzr
    ret = run(*run_argv)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/commands.py", line 375, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/builtins.py", line 2226, in run
    reporter=reporter, revprops=properties)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/workingtree_4.py", line 245, in commit
    result = WorkingTree3.commit(self, message, revprops, *args, **kwargs)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/decorators.py", line 165, in write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/mutabletree.py", line 195, in commit
    revprops=revprops, *args, **kwargs)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/commit.py", line 292, in commit
    self._remove_deleted()
  File "/usr/local/lib/python2.4/site-packages/bzrlib/commit.py", line 583, in _remove_deleted
    self.work_tree.unversion(deleted_ids)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/mutabletree.py", line 38, in tree_write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/local/lib/python2.4/site-packages/bzrlib/workingtree_4.py", line 1188, in unversion
    if (entry[1][0][0] == 'a'
  File "/usr/local/lib/python2.4/site-packages/bzrlib/dirstate.py", line 2068, in _make_absent
    assert update_tree_details[0][0] != 'a' # absent
AssertionError

bzr 0.17.0 on python 2.4.3.final.0 (linux2)
arguments: ['/usr/local/bin/bzr', 'commit', '-m', 'massive merge']