unexpected end of regular expression

I've just did bzr add in my project directory and got this (and i have the same error using bzr ignore ./ignorefile):

bzr: ERROR: sre_constants.error: unexpected end of regular expression

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 384, in run
    no_recurse, action=action, save=not dry_run)
  File "/usr/lib/python2.5/site-packages/bzrlib/mutabletree.py", line 51, in tree_write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/mutabletree.py", line 417, in smart_add
    ignore_glob = self.is_ignored(subp)
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree.py", line 1669, in is_ignored
    return self._ignoreglobster.match(filename)
  File "/usr/lib/python2.5/site-packages/bzrlib/globbing.py", line 213, in match
    match = regex.match(filename)
  File "/usr/lib/python2.5/site-packages/bzrlib/lazy_regex.py", line 69, in __getattr__
    self._compile_and_collapse()
  File "/usr/lib/python2.5/site-packages/bzrlib/lazy_regex.py", line 55, in _compile_and_collapse
    **self._regex_kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/lazy_regex.py", line 61, in _real_re_compile
    return _real_re_compile(*args, **kwargs)
  File "re.py", line 180, in compile
    return _compile(pattern, flags)
  File "re.py", line 233, in _compile
    raise error, v # invalid expression
error: unexpected end of regular expression

bzr 1.0.0 on python 2.5.1.final.0 (linux2)
arguments: ['/usr/bin/bzr', 'add']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'
plugins:
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [unknown]
  multiparent /usr/lib/python2.5/site-packages/bzrlib/plugins/multiparent.pyc [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.