WebSphere MQ 8, 7.5 RA: wrong xa exception return code on second rollback agains the same xid

Second rollback against the same Xid is JTS spec compliant and
this could be ignored. When RAR does not know such Xid then XAER_NOTA
response is expected. But IBM Websphere could return rather XAER_RMFAIL
which is incorrect. The method 'xa_rollback' has failed with errorCode '-7' due to the resource being closed.' 

Customer impact:
This has no impact for data consistency. Only issue are logged warnings in server log.