Fix a data race

consumer.go

@@ -610,7 +610,10 @@ func (bc *brokerConsumer) handleResponses() {
 			close(child.trigger)
 			delete(bc.subscriptions, child)
 		default:
-			switch child.responseResult {
+			result := child.responseResult
+			child.responseResult = nil
+
+			switch result {
 			case nil:
 				break
 			case errTimedOut:
@@ -620,26 +623,24 @@ func (bc *brokerConsumer) handleResponses() {
 			case ErrOffsetOutOfRange:
 				// there's no point in retrying this it will just fail the same way again
 				// shut it down and force the user to choose what to do
-				child.sendError(child.responseResult)
-				Logger.Printf("consumer/%s/%d shutting down because %s\n", child.topic, child.partition, child.responseResult)
+				child.sendError(result)
+				Logger.Printf("consumer/%s/%d shutting down because %s\n", child.topic, child.partition, result)
 				close(child.trigger)
 				delete(bc.subscriptions, child)
 			case ErrUnknownTopicOrPartition, ErrNotLeaderForPartition, ErrLeaderNotAvailable:
 				// not an error, but does need redispatching
 				Logger.Printf("consumer/broker/%d abandoned subscription to %s/%d because %s\n",
-					bc.broker.ID(), child.topic, child.partition, child.responseResult)
+					bc.broker.ID(), child.topic, child.partition, result)
 				child.trigger <- none{}
 				delete(bc.subscriptions, child)
 			default:
 				// dunno, tell the user and try redispatching
-				child.sendError(child.responseResult)
+				child.sendError(result)
 				Logger.Printf("consumer/broker/%d abandoned subscription to %s/%d because %s\n",
-					bc.broker.ID(), child.topic, child.partition, child.responseResult)
+					bc.broker.ID(), child.topic, child.partition, result)
 				child.trigger <- none{}
 				delete(bc.subscriptions, child)
 			}
-
-			child.responseResult = nil
 		}
 	}
 }