From the Robot point of view, this looks [0] like CONTROLLER-1714 but the karaf.log [1] looks more like CONTROLLER-1706.

As there are new undelivered messages, and this is seen in a different test scenario, I do not think this is just a duplicate of CONTROLLER-1706.

The first new message is:
2017-06-11 10:10:46,360 | INFO | lt-dispatcher-44 | RepointableActorRef | 174 - com.typesafe.akka.slf4j - 2.4.18 | Message [org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListenerReply] from Actorakka://opendaylight-cluster-data/user/shardmanager-config/member-2-shard-id-ints!-config/member-2-shard-id-ints!-config-notifier#-358600829 to Actorakka://opendaylight-cluster-data/user/$n#686259085 was not delivered. [2] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

The last:
2017-06-11 10:10:46,426 | INFO | lt-dispatcher-44 | RepointableActorRef | 174 - com.typesafe.akka.slf4j - 2.4.18 | Message [org.opendaylight.controller.cluster.notifications.RoleChangeNotification] from Actorakka://opendaylight-cluster-data/user/shardmanager-config/member-2-shard-id-ints!-config/member-2-shard-id-ints!-config-notifier#-358600829 to Actorakka://opendaylight-cluster-data/user/$n#686259085 was not delivered. [10] dead letters encountered, no more dead letters will be logged. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/739/log.html.gz#s1-s26-t1-k2-k9
[1] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/739/odl2_karaf.log.gz