push to a new location fails

for backup purposes, i created a new bzr repository on an external drive and pushed my local tree to that repository. that gave me following error (the local tree has unicode content):

bzr: ERROR: exceptions.UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 181: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/bzrlib/commands.py", line 926, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/pymodules/python2.6/bzrlib/commands.py", line 1126, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/pymodules/python2.6/bzrlib/commands.py", line 691, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/pymodules/python2.6/bzrlib/commands.py", line 713, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/pymodules/python2.6/bzrlib/cleanup.py", line 135, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/pymodules/python2.6/bzrlib/cleanup.py", line 165, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/pymodules/python2.6/bzrlib/builtins.py", line 1132, in run
    use_existing_dir=use_existing_dir, no_tree=no_tree)
  File "/usr/lib/pymodules/python2.6/bzrlib/push.py", line 91, in _show_push_branch
    no_tree=no_tree)
  File "/usr/lib/pymodules/python2.6/bzrlib/branch.py", line 1409, in create_clone_on_transport
    no_tree=no_tree)
  File "/usr/lib/pymodules/python2.6/bzrlib/bzrdir.py", line 270, in clone_on_transport
    self.open_workingtree().clone(result)
  File "/usr/lib/pymodules/python2.6/bzrlib/decorators.py", line 140, in read_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/pymodules/python2.6/bzrlib/workingtree.py", line 651, in clone
    result = to_bzrdir.create_workingtree()
  File "/usr/lib/pymodules/python2.6/bzrlib/bzrdir.py", line 1293, in create_workingtree
    accelerator_tree=accelerator_tree, hardlink=hardlink)
  File "/usr/lib/pymodules/python2.6/bzrlib/workingtree_4.py", line 1475, in initialize
    delta_from_tree=delta_from_tree)
  File "/usr/lib/pymodules/python2.6/bzrlib/transform.py", line 2417, in build_tree
    delta_from_tree)
  File "/usr/lib/pymodules/python2.6/bzrlib/transform.py", line 2516, in _build_tree
    accelerator_tree, hardlink)
  File "/usr/lib/pymodules/python2.6/bzrlib/transform.py", line 2586, in _create_files
    ContentFilterContext(tree_path, tree))
  File "/usr/lib/pymodules/python2.6/bzrlib/filters/__init__.py", line 170, in filtered_output_bytes
    chunks = filter.writer(chunks, context)
  File "/home/name/.bazaar/plugins/keywords/keywords.py", line 259, in _normal_kw_expander
    return _kw_expander(chunks, context)
  File "/home/name/.bazaar/plugins/keywords/keywords.py", line 254, in _kw_expander
    encoder=encoder)]
  File "/home/name/.bazaar/plugins/keywords/keywords.py", line 221, in expand_keywords
    return result + rest
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 181: ordinal not in range(128)