Comment 0 for bug 1796161

==> /var/log/maas/regiond.log <==
2018-10-04 18:32:34 regiond: [info] 10.245.136.6 GET /MAAS/rpc/ HTTP/1.1 --> 200 OK (referrer: -; agent: provisioningserver.rpc.clusterservice.ClusterClientService)
2018-10-04 18:32:34 maasserver.listener: [critical] Failure while handling notification to 'resourcepool': ''
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 500, in errback
     self._startRunCallbacks(fail)
   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)
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
     result = result.throwExceptionIntoGenerator(g)
   File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
     return g.throw(self.type, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/maasserver/websockets/protocol.py", line 421, in onNotify
     self.processNotify, handler, channel, action, obj_id)
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 250, in inContext
     result = inContext.theWork()
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 266, in <lambda>
     inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 883, in callInContext
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 232, in wrapper
     result = func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 756, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 563, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python3.6/contextlib.py", line 52, in inner
     return func(*args, **kwds)
   File "/usr/lib/python3/dist-packages/maasserver/websockets/protocol.py", line 428, in processNotify
     return handler.on_listen(channel, action, obj_id)
   File "/usr/lib/python3/dist-packages/maasserver/websockets/base.py", line 465, in on_listen
     pk = self._meta.pk_type(pk)
 builtins.ValueError: invalid literal for int() with base 10: ''