Steps to reproduce:
1. Create a consumer on a topic.
2. Disconnect the broker (easiest is to shut it down).
3. Destroy the consumer while the low-level failover is retrying to connect.
4. Bring the broker online and let the failover reconnect.
A zombie consumer is re-created on the topic. This will eventually lead to producer flow-control kicking in because it will never acknowledge messages sent to it.