Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/defer/__init__.py", line 389, in _next
    self.result = callback(self.result, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/defer/utils.py", line 64, in <lambda>
    deferred.add_errback(lambda error: dbus_errback(error.value))
  File "/usr/lib/python2.7/dist-packages/dbus/service.py", line 669, in <lambda>
    keywords[error_callback] = lambda exception: _method_reply_error(connection, message, exception)
NameError: global name '_method_reply_error' is not defined