When docker is stopped, docker-py receive a empty string

I have a daemon that wait on docker with c.events().

When I restart docker, it fail with :

      File "./dockerdns.py", line 532, in loop
        for e in self.c.events():
      File "/usr/lib/python2.6/site-packages/docker/client.py", line 233, in _stream_helper
        size = int(size_line, 16)

I'm running this on a Redhat 6, with standard python (2.6.6)
This small patch should avoid that.