[concert_conductor] uninvited to gone error

[jihoonl]

[INFO] [WallTime: 1418793006.105336] Conductor : concert client transition [uninvited->gone][young1]
Traceback (most recent call last):
  File "/home/yujin/ros/yujinrnd/src/rocon_concert/concert_conductor/scripts/conductor.py", line 22, in <module>
    conductor.spin()
  File "/home/yujin/ros/yujinrnd/src/rocon_concert/concert_conductor/src/concert_conductor/conductor.py", line 101, in spin
    self._concert_clients.update(remote_gateways)
  File "/home/yujin/ros/yujinrnd/src/rocon_concert/concert_conductor/src/concert_conductor/concert_clients.py", line 171, in update
    result = self._state_handlers[concert_client.state](None, concert_client)
  File "/home/yujin/ros/yujinrnd/src/rocon_concert/concert_conductor/src/concert_conductor/concert_clients.py", line 322, in _update_uninvited_client
    self._local_gateway.request_pulls(remote_gateway.name, cancel=True, service_names=['invite'], topic_names=[])
AttributeError: 'NoneType' object has no attribute 'name'