Consider the following case:
1. A prepares a transaction for key K on nodes B and C.
2. The primary owner B acquires and registers this lock.
3. The cluster partitions and A,C remain in partition one, and B in a separate partition.
4. The transaction rolls back. However, since B left the cluster, the rollback will not be sent to B.
5. B rejoins the cluster. It still has a lock acquired for key K.
This can lead to a lock being acquired indefinitely.