tweak comment

brokerManager.go

@@ -96,8 +96,10 @@ func (bm *brokerManager) tryLeader(topic string, partition int32, req encoder, r
 	delete(bm.brokers, b.id)
 	bm.brokersLock.Unlock()
 
-	// then do the whole thing again treating all errors as fatal
+	// then do the whole thing again
 	// (the metadata for the broker gets refreshed automatically in getLeader)
+	// if we get a broker here, it's guaranteed to be fresh, so if it fails then
+	// we pass that error back to the user (as opposed to retrying indefinitely)
 	b, err = bm.getLeader(topic, partition)
 	if err != nil {
 		return err