'bzr help commands' crashes when qt not correctly installed (seen on mac os x)

MACDE****:/ j****$ bzr help commands
bzr: ERROR: exceptions.ImportError: dlopen(/Library/Python/2.6/site-packages/PyQt4/QtCore.so, 2): Library not loaded: QtCore.framework/Versions/4/QtCore
  Referenced from: /Library/Python/2.6/site-packages/PyQt4/QtCore.so
  Reason: image not found

Traceback (most recent call last):
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 853, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 1055, in run_bzr
    ret = run(*run_argv)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 661, in run_argv_aliases
    return self.run_direct(**all_cmd_args)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 665, in run_direct
    return self._operation.run_simple(*args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/cleanup.py", line 122, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/cleanup.py", line 156, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 1070, in ignore_pipe
    result = func(*args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/builtins.py", line 4192, in run
    bzrlib.help.help(topic)
  File "/Library/Python/2.6/site-packages/bzrlib/help.py", line 52, in help
    outfile.write(source.get_help_text(shadowed_terms))
  File "/Library/Python/2.6/site-packages/bzrlib/help_topics/__init__.py", line 849, in get_help_text
    result = topic_registry.get_detail(self.topic)
  File "/Library/Python/2.6/site-packages/bzrlib/help_topics/__init__.py", line 90, in get_detail
    return obj(topic)
  File "/Library/Python/2.6/site-packages/bzrlib/help.py", line 78, in _help_commands_to_text
    shown_commands = [(n, o) for n, o in commands if o.hidden == hidden]
  File "/Library/Python/2.6/site-packages/bzrlib/help.py", line 77, in <genexpr>
    commands = ((n, _mod_commands.get_cmd_object(n)) for n in names)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 213, in get_cmd_object
    return _get_cmd_object(cmd_name, plugins_override)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 233, in _get_cmd_object
    cmd = hook(cmd, cmd_name)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 306, in _get_plugin_command
    return plugin_cmds.get(cmd_name)()
  File "/Library/Python/2.6/site-packages/bzrlib/registry.py", line 173, in get
    return self._dict[self._get_key_or_default(key)].get_obj()
  File "/Library/Python/2.6/site-packages/bzrlib/registry.py", line 61, in get_obj
    self._do_import()
  File "/Library/Python/2.6/site-packages/bzrlib/registry.py", line 70, in _do_import
    obj = __import__(self._module_name, globals(), locals(), names)
  File "/Library/Python/2.6/site-packages/bzrlib/plugins/qbzr/lib/subprocess.py", line 30, in <module>
    from PyQt4 import QtCore, QtGui
ImportError: dlopen(/Library/Python/2.6/site-packages/PyQt4/QtCore.so, 2): Library not loaded: QtCore.framework/Versions/4/QtCore
  Referenced from: /Library/Python/2.6/site-packages/PyQt4/QtCore.so
  Reason: image not found

bzr 2.1.0rc1 on python 2.6.1 (Darwin-10.2.0-i386-64bit)
arguments: ['/usr/local/bin/bzr', 'help', 'commands']
encoding: 'UTF-8', fsenc: 'utf-8', lang: 'fr_CH.UTF-8'
plugins:
  bzrtools /Library/Python/2.6/site-packages/bzrlib/plugins/bzrtools [2.1.0b1]
  email /Library/Python/2.6/site-packages/bzrlib/plugins/email [unknown]
  explorer /Library/Python/2.6/site-packages/bzrlib/plugins/explorer [0.11.2]
  keychain /Library/Python/2.6/site-packages/bzrlib/plugins/keychain [0.1.0]
  launchpad /Library/Python/2.6/site-packages/bzrlib/plugins/launchpad [2.1.0rc1]
  netrc_credential_store /Library/Python/2.6/site-packages/bzrlib/plugins/netrc_credential_store [2.1.0rc1]
  news_merge /Library/Python/2.6/site-packages/bzrlib/plugins/news_merge [2.1.0rc1]
  qbzr /Library/Python/2.6/site-packages/bzrlib/plugins/qbzr [0.18.0]
  rebase /Library/Python/2.6/site-packages/bzrlib/plugins/rebase [0.5.5]
  svn /Library/Python/2.6/site-packages/bzrlib/plugins/svn [1.0.1]
  upload /Library/Python/2.6/site-packages/bzrlib/plugins/upload [1.0.0dev]
  xmloutput /Library/Python/2.6/site-packages/bzrlib/plugins/xmloutput [0.8.5]