Torflow traceback: ZeroDivisionError: float division

Traceback (most recent call last):
  File "../../TorCtl/TorCtl.py", line 720, in _eventLoop
    self._handleFn(timestamp, reply)
  File "../../TorCtl/TorCtl.py", line 1346, in _handle1
    self._map1.get(event.event_name, self.unknown_event)(event)
  File "../../TorCtl/PathSupport.py", line 1837, in new_consensus_event
    TorCtl.ConsensusTracker.new_consensus_event(self, n)
  File "../../TorCtl/TorCtl.py", line 1694, in new_consensus_event
    self._read_routers(self.ns_map.values())
  File "../../TorCtl/TorCtl.py", line 1653, in _read_routers
    ratio_r.sort(lambda x, y: cmp(float(y.bw)/y.get_unmeasured_bw(),
  File "../../TorCtl/TorCtl.py", line 1654, in <lambda>
    float(x.bw)/x.get_unmeasured_bw()))
ZeroDivisionError: float division

Preceded by

WARN[Thu Feb 28 23:02:26 2013]:No event for: 650 NEWCONSENSUS

and post-ceded by

NOTICE[Thu Feb 28 23:02:26 2013]:Tor closed control connection. Exiting event thread.
WARN[Thu Feb 28 23:02:26 2013]:Child process recieved SIGTERM
INFO[Thu Feb 28 23:02:26 2013]:Beginning time loop
DEBUG[Thu Feb 28 23:02:27 2013]:Child Process Spawning...
INFO[Thu Feb 28 23:02:27 2013]:Connecting to Tor at 127.0.0.1:9111

so it looks like it took down something-er-other too.