NullPointerException after remove-shard-replica

While investigating a recent failure [0] (looks like CONTROLLER-1707 duplicate) which replaced CONTROLLER-1706 (perhaps because CONTROLLER-1512 fixes were merged to stable/carbon), a spotted a NPE (causing failed transaction chain) in karaf.log [1]:

2017-06-11 11:49:49,724 | WARN | ult-dispatcher-2 | ConcurrentDOMDataBroker | 199 - org.opendaylight.controller.sal-distributed-datastore - 1.5.1.Carbon | Tx: DOM-CHAIN-1-3057 Error during phase CAN_COMMIT, starting Abort
java.lang.NullPointerException
at org.opendaylight.controller.cluster.datastore.ShardDataTree.startCanCommit(ShardDataTree.java:810)
at org.opendaylight.controller.cluster.datastore.SimpleShardDataTreeCohort.canCommit(SimpleShardDataTreeCohort.java:105)
at org.opendaylight.controller.cluster.datastore.ChainedCommitCohort.canCommit(ChainedCommitCohort.java:58)
at org.opendaylight.controller.cluster.datastore.FrontendReadWriteTransaction.directCommit(FrontendReadWriteTransaction.java:384)
at org.opendaylight.controller.cluster.datastore.FrontendReadWriteTransaction.handleModifyTransaction(FrontendReadWriteTransaction.java:527)
at org.opendaylight.controller.cluster.datastore.FrontendReadWriteTransaction.doHandleRequest(FrontendReadWriteTransaction.java:174)
at org.opendaylight.controller.cluster.datastore.FrontendTransaction.handleRequest(FrontendTransaction.java:141)
at org.opendaylight.controller.cluster.datastore.AbstractFrontendHistory.handleTransactionRequest(AbstractFrontendHistory.java:154)
at org.opendaylight.controller.cluster.datastore.LeaderFrontendState.handleTransactionRequest(LeaderFrontendState.java:210)
at org.opendaylight.controller.cluster.datastore.Shard.handleRequest(Shard.java:462)
at org.opendaylight.controller.cluster.datastore.Shard.handleNonRaftCommand(Shard.java:293)
at org.opendaylight.controller.cluster.raft.RaftActor.handleCommand(RaftActor.java:270)
at org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor.onReceiveCommand(AbstractUntypedPersistentActor.java:31)
at akka.persistence.UntypedPersistentActor.onReceive(PersistentActor.scala:170)
at org.opendaylight.controller.cluster.common.actor.MeteringBehavior.apply(MeteringBehavior.java:104)
at akka.actor.ActorCell$$anonfun$become$1.applyOrElse(ActorCell.scala:544)
at akka.actor.Actor$class.aroundReceive(Actor.scala:502)
at akka.persistence.UntypedPersistentActor.akka$persistence$Eventsourced$$super$aroundReceive(PersistentActor.scala:168)
at akka.persistence.Eventsourced$$anon$1.stateReceive(Eventsourced.scala:727)
at akka.persistence.Eventsourced$class.aroundReceive(Eventsourced.scala:183)
at akka.persistence.UntypedPersistentActor.aroundReceive(PersistentActor.scala:168)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:526)
at akka.actor.ActorCell.invoke(ActorCell.scala:495)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
at akka.dispatch.Mailbox.run(Mailbox.scala:224)
at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/739/log.html.gz#s1-s36-t1-k2-k14
[1] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/739/odl2_karaf.log.gz