Ensure recovery from WAL connects servers.
Make an error on request to another server send the message down the response channel (non-blocking) so that go routines monitoring the channel and not the method return can stop.
Handle access denied responses to close out stream. Close the seriesWriter when a list series query is done.
Lock the connection when setting it on the protobuf client.
Make list series engine not yield empty response, which was breaking the test when shards didn't have any series.