Comment 0 for bug 1824171

Rack/Region communications seem to fail causing timeouts for image downloads.

2019-04-09 16:13:33 maasserver.rpc.regionservice: [critical] Failed to register rack controller 'qfnrdf' with the master. Connection will be dropped.
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 567, in _startRunCallbacks
     self._runCallbacks()
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 653, in _runCallbacks
     current.result = callback(current.result, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1442, in gotResult
     _inlineCallbacks(r, g, deferred)
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1386, in _inlineCallbacks
     result = g.send(result)
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/maasserver/rpc/regionservice.py", line 687, in _register
     yield self.initResponder(rack_controller)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 161, in wrapper
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/rpc/regionservice.py", line 610, in initResponder
     self.host = self.transport.getHost()
 builtins.AttributeError: 'NoneType' object has no attribute 'getHost'