storage/ndb/test/ndbapi/test_event.cpp:
  test applier under merge events
  also fix run in 5.1 (check for data event)
storage/ndb/test/run-test/daily-devel-tests.txt:
  add: test_event -n MergeEventOperationApplier_NR
storage/ndb/src/ndbapi/NdbEventOperationImpl.cpp:
  allow idempotency INSoINS or DELoDEL
  does NOT check data section 2 (before data)