Socket reconnection on retries of JoinGroup, SyncGroup, LeaveGroup

[saich]

Today, if JoinGroup sees a socket disconnection, it will retry again without reconnecting the connection which results in subsequent retries all to fail.

This change will ensure that we attempt to reconnect the connection if see a disconnected connection while selecting a unique RequestHandler to use for this request.

Alternative approaches that can be considered:

• Reconnect automatically in RequestHandler.request before calling self.shared.requests.put
• Reconnect automatically in BrokerConnection.request if required

[codecov-io]

Codecov Report

Merging #939 into master will increase coverage by 0.09%.
The diff coverage is 66.66%.

@@ Coverage Diff @@ ## master #939 +/- ## ========================================== + Coverage 83.32% 83.41% +0.09%  ========================================== Files 36 36 Lines 3807 3811 +4 Branches 562 563 +1 ========================================== + Hits 3172 3179 +7  + Misses 489 486 -3  Partials 146 146

Impacted Files	Coverage Δ
pykafka/managedbalancedconsumer.py	84.1% <100%> (ø)	⬆️
pykafka/broker.py	88.13% <60%> (-5.51%)	⬇️
pykafka/connection.py	83.16% <0%> (-1.99%)	⬇️
pykafka/topic.py	80.41% <0%> (-1.04%)	⬇️
pykafka/balancedconsumer.py	91.22% <0%> (+1.16%)	⬆️
pykafka/simpleconsumer.py	86.6% <0%> (+1.56%)	⬆️
pykafka/cluster.py	71.89% <0%> (+1.82%)	⬆️

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[emmettbutler]

Thanks for the contribution. I think your first alternate suggestion of putting this functionality in RequestHandler might be a better way to maintain encapsulation.