Rely on the call to zk.exists? to check that.
I've noticed that the threaded connection has a :retry_duration which would allow for temporary disconnections to be recovered from, but this check to zk.connected? prevents that from working.
This way, we can let the call to zk.exists? do the job of checking if we're connected, and it will place nice with reconnection.
Don't check connection state in Locker#assert!
Rely on the call to zk.exists? to check that