Solr currently, upon receiving the stop command, removes its entry from the zk /live_nodes znode after it has finished processing all inflight requests, just before finally shutting down.
In this case, any applications that depend on a solr node's live_node entry to decide whether or not to query it fail once the stop command has been executed but solr has not yet fully shut down.
Something similar occurs during startup of a solr node. The solr node seems to add it's entry to the /live_nodes in zk once it is up but before it has started accepting requests and once again, this causes dependent applications to fail in a similar fashion.
Hence, removal of the node entry and addition of the same to the zk live_nodes immediately upon shutting down and at the very end upon coming up respectively will greatly benefit applications that depend the live_nodes znode.