Exception when getting help for a module

python
Python 2.7.2+ (default, Oct 4 2011, 20:06:09)
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import bzrlib.Branch
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named Branch
>>> import bzrlib.branch
>>> help(bzrlib.branch)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/site.py", line 469, in __call__
    return pydoc.help(*args, **kwds)
  File "/usr/lib/python2.7/pydoc.py", line 1728, in __call__
    self.help(request)
  File "/usr/lib/python2.7/pydoc.py", line 1775, in help
    else: doc(request, 'Help on %s:')
  File "/usr/lib/python2.7/pydoc.py", line 1512, in doc
    pager(render_doc(thing, title, forceload))
  File "/usr/lib/python2.7/pydoc.py", line 1507, in render_doc
    return title % desc + '\n\n' + text.document(object, name)
  File "/usr/lib/python2.7/pydoc.py", line 329, in document
    if inspect.ismodule(object): return self.docmodule(*args)
  File "/usr/lib/python2.7/pydoc.py", line 1089, in docmodule
    inspect.getclasstree(classlist, 1), name)]
  File "/usr/lib/python2.7/inspect.py", line 729, in getclasstree
    if c.__bases__:
  File "/usr/lib/python2.7/dist-packages/bzrlib/lazy_import.py", line 110, in __getattribute__
    obj = _replace()
  File "/usr/lib/python2.7/dist-packages/bzrlib/lazy_import.py", line 89, in _replace
    extra=e)
bzrlib.errors.IllegalUseOfScopeReplacer: ScopeReplacer object 'BasicTags' was used incorrectly: Object already cleaned up, did you assign it to another variable?: _factory
>>> bzrlib.__version__
'2.4.1'
>>> file('/etc/lsb-release').read()
'DISTRIB_ID=Ubuntu\nDISTRIB_RELEASE=11.10\nDISTRIB_CODENAME=oneiric\nDISTRIB_DESCRIPTION="Ubuntu 11.10"\n'
>>>