errors when a network doesn't have an ip address

[AskAlice]

Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/gevent/greenlet.py", line 327, in run
    result = self._run(*self.args, **self.kwargs)
  File "./dockerdns", line 175, in run
    for rec in self._inspect(container['Id']):
  File "./dockerdns", line 245, in _inspect
    ip_addrs = self._get_addrs(networks)
  File "./dockerdns", line 229, in _get_addrs
    return [ value['IPAddress'] for value in networks.values() ]
AttributeError: 'NoneType' object has no attribute 'values'
<Greenlet at 0x73f3a896a7d0: <bound method DockerMonitor.run of <__main__.DockerMonitor object at 0x73f3a90d13d0>>> failed with AttributeError