An unexpected node crash and delayed messages would fail the job

Related cluster configuration:

• MAX_FETCH_FAILURES_NOTIFICATIONS is 3
• NodeManager recovery is disabled

Bug scenario:

1. submit a wordcount job which contains 2 simple map tasks (map_0 and map_1) and 1 simple reduce task (reduce_0);
2. all map tasks were finished successfully and the AppMaster was notified;
3. the NodeManager which runs the map task map_1 crashes;
4. the AppMaster schedules a reduce attempt;
5. the reduce attempt sends statusUpdate message to AppMaster to notify a fetch failure;
6. the reduce attempt fails due to Shuffle$ShuffleError which was caused by java.io.IOException: Exceeded MAX_FAILED_UNIQUE_FETCHES; bailing-out;
7. the reduce attempt send message fatalError to AppMaster
8. the AppMaster successively reschedules another three reduce attempts, but all of them were failed due to Shuffle$ShuffleError;
9. AppMaster fails the wordcount job due to the failed reduce task;
10. AppMaster receives three statusUpdate messages that state a fetch failure like the message in step 5, but it has already failed the job and would not rerun the task map_1.