When one of the targets of a PrepareCommand leaves, the originator receives a SuspectException and tries to roll back the transaction. However, the 

RollbackCommand can also fail with with a SuspectException if:
* syncRollbackPhase = true (the default, since ISPN-4137)
* The cache topology hasn't been updated to exclude the leaver yet (maybe because it was the old coordinator that left)

In that case, we could throw a SuspectException in JGroupsTransport.invokeRemotely without sending the RollbackCommand to the other owner:
23:34:01,219 ERROR [org.infinispan.interceptors.InvocationContextInterceptor] (PrivateLogChecker-4) ISPN000136: Execution error
org.infinispan.remoting.transport.jgroups.SuspectException: One or more nodes have left the cluster while replicating command RollbackCommand {gtx=GlobalTransaction:<edg-perf08-52473>:1077:local, cacheName='testCache', topologyId=8}
	at org.infinispan.remoting.transport.jgroups.JGroupsTransport.invokeRemotely(JGroupsTransport.java:486)
	at org.infinispan.remoting.rpc.RpcManagerImpl.invokeRemotely(RpcManagerImpl.java:281)
	at org.infinispan.interceptors.distribution.TxDistributionInterceptor.visitRollbackCommand(TxDistributionInterceptor.java:223)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:112)
	at org.infinispan.commands.AbstractVisitor.visitRollbackCommand(AbstractVisitor.java:101)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.locking.AbstractTxLockingInterceptor.visitRollbackCommand(AbstractTxLockingInterceptor.java:51)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.NotificationInterceptor.visitRollbackCommand(NotificationInterceptor.java:50)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.TxInterceptor.visitRollbackCommand(TxInterceptor.java:207)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:112)
	at org.infinispan.commands.AbstractVisitor.visitRollbackCommand(AbstractVisitor.java:101)
	at org.infinispan.statetransfer.TransactionSynchronizerInterceptor.visitRollbackCommand(TransactionSynchronizerInterceptor.java:66)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.statetransfer.StateTransferInterceptor.handleTopologyAffectedCommand(StateTransferInterceptor.java:222)
	at org.infinispan.statetransfer.StateTransferInterceptor.handleTxCommand(StateTransferInterceptor.java:153)
	at org.infinispan.statetransfer.StateTransferInterceptor.visitRollbackCommand(StateTransferInterceptor.java:91)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:112)
	at org.infinispan.commands.AbstractVisitor.visitRollbackCommand(AbstractVisitor.java:101)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:98)
	at org.infinispan.interceptors.InvocationContextInterceptor.handleAll(InvocationContextInterceptor.java:110)
	at org.infinispan.interceptors.InvocationContextInterceptor.handleDefault(InvocationContextInterceptor.java:73)
	at org.infinispan.commands.AbstractVisitor.visitRollbackCommand(AbstractVisitor.java:101)
	at org.infinispan.commands.tx.RollbackCommand.acceptVisitor(RollbackCommand.java:40)
	at org.infinispan.interceptors.InterceptorChain.invoke(InterceptorChain.java:333)
	at org.infinispan.transaction.TransactionCoordinator.rollbackInternal(TransactionCoordinator.java:237)
	at org.infinispan.transaction.TransactionCoordinator.rollback(TransactionCoordinator.java:172)
	at org.infinispan.transaction.TransactionCoordinator.prepare(TransactionCoordinator.java:140)
	at org.infinispan.transaction.TransactionCoordinator.prepare(TransactionCoordinator.java:104)
	at org.infinispan.transaction.synchronization.SynchronizationAdapter.beforeCompletion(SynchronizationAdapter.java:44)
	at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:76)
	at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:273)
	at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:93)
	at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:164)
	at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1165)
	at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:117)
	at org.infinispan.CacheImpl.executeCommandAndCommitIfNeeded(CacheImpl.java:1436)
	at org.infinispan.CacheImpl.putInternal(CacheImpl.java:904)
	at org.infinispan.CacheImpl.put(CacheImpl.java:896)
	at org.infinispan.CacheImpl.put(CacheImpl.java:1471)
	at org.infinispan.CacheImpl.put(CacheImpl.java:231)
	at org.radargun.cachewrappers.InfinispanBasicOperations.put(InfinispanBasicOperations.java:25)
	at org.radargun.cachewrappers.Infinispan51BasicOperations.put(Infinispan51BasicOperations.java:31)
	at org.radargun.cachewrappers.Infinispan52BasicOperations.put(Infinispan52BasicOperations.java:16)
	at org.radargun.cachewrappers.InfinispanWrapper.put(InfinispanWrapper.java:185)
	at org.radargun.stressors.LogChecker.run(LogChecker.java:106)

The RollbackCommand should have the SYNCHRONOUS_IGNORE_LEAVERS ResponseMode, so that the owner still alive receives the the command. Otherwise, that stale transaction will never be completed.