File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/collection.py", line 598, in find_one

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/cursor.py", line 814, in next

    if len(self.__data) or self._refresh():

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/cursor.py", line 763, in _refresh

    self.__uuid_subtype))

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/cursor.py", line 700, in __send_message

    **kwargs)

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/mongo_replica_set_client.py", line 1203, in _send_message_with_response

    latency=secondary_acceptable_latency_ms)    

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/read_preferences.py", line 170, in select_member

    members, SECONDARY, tag_sets, latency)

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/read_preferences.py", line 162, in select_member

    candidate = select_member_with_tags(members, tags, True, latency)

  File "/usr/local/python/env/prod_live/lib/python2.6/site-packages/pymongo/read_preferences.py", line 127, in select_member_with_tags

    return random.choice(near_candidates)

  File "/usr/local/python/lib/python2.6/random.py", line 261, in choice

    return seq[int(self.random() * len(seq))]  # raises IndexError if seq is empty