unsubscribe-ddtl does not return when shard moves

This has happened in test which starts produce-transactions (which means prefix-based shards and tell-based protocol) on each member, registers one listener on the Leader member. The test itself passed most of the steps, just the final unsubscribe-ddtl call has not returned [0] within 30 seconds.

Karaf.log shows [1] an unexpected UnreachableMember at 23:34:24,787 but the producers finished correctly [2]. Contrary to that, there is nothing in the karaf.log after 23:34:43,427, so no clue why unsubscribe-ddtl failed to respond.

Note that the examined run has used odl-restconf, but the following runs are using odl-restconf-noauth instead.

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/686/archives/log.html.gz#s1-s43-t1-k2-k15-k2-k1-k4-k6-k1
[1] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/686/archives/odl2_karaf.log.gz
[2] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/686/archives/log.html.gz#s1-s43-t1-k2-k13