maried does not recover from network hiccup

[dsprenkels]

Traceback from maried after a short DNS hiccup:

Traceback (most recent call last):
  File "/home/maried/py/maried/gstreamer.py", line 302, in _on_about_to_finish
    self.on_about_to_finish()
  File "/home/maried/py/sarah/event.py", line 8, in __call__
    handler(*args, **kwargs)
  File "/home/maried/py/maried/core.py", line 376, in _player_on_about_to_finish
    self._queue_next()
  File "/home/maried/py/maried/core.py", line 324, in _queue_next
    self.player.queue(media)
  File "/home/maried/py/maried/gstreamer.py", line 230, in queue
    stream = mf.open()
  File "/home/maried/py/maried/_bertha.py", line 13, in open
    return self.store._open(self.key)
  File "/home/maried/py/maried/_bertha.py", line 59, in _open
    return self.c.get(key)
  File "/home/maried/py/bertha/client.py", line 142, in get
    sock = self._connect()
  File "/home/maried/py/bertha/client.py", line 205, in _connect
    socket.SOCK_STREAM):
socket.gaierror: [Errno -2] Name or service not known

berthad gives back an error because the DNS service is unreachable, but maried does not retry to retrieve the file.