Transient test failure: KafkaConsumerTest.testChangingRegexSubscription

https://builds.apache.org/job/kafka-trunk-jdk8/1647/testReport/junit/org.apache.kafka.clients.consumer/KafkaConsumerTest/testChangingRegexSubscription/:

java.lang.IllegalStateException: Request matcher did not match next-in-line request (group_id=mock-group,session_timeout=30000,rebalance_timeout=60000,member_id=memberId,protocol_type=consumer,group_protocols=[(protocol_name=roundrobin,protocol_metadata=java.nio.HeapByteBuffer(pos=10 lim=10 cap=10)))
at org.apache.kafka.clients.MockClient.send(MockClient.java:156)
at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.trySend(ConsumerNetworkClient.java:409)
at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:223)
at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:208)
at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:168)
at org.apache.kafka.clients.consumer.internals.AbstractCoordinator.joinGroupIfNeeded(AbstractCoordinator.java:358)
at org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureActiveGroup(AbstractCoordinator.java:310)
at org.apache.kafka.clients.consumer.internals.ConsumerCoordinator.poll(ConsumerCoordinator.java:297)
at org.apache.kafka.clients.consumer.KafkaConsumer.pollOnce(KafkaConsumer.java:1051)
at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1016)
at org.apache.kafka.clients.consumer.KafkaConsumerTest.testChangingRegexSubscription(KafkaConsumerTest.java:650)