MAPREDUCE-5562. Fixed MR App Master to perform pending tasks like staging-dir cleanup, sending job-end notification correctly when unregister with RM fails. Contributed by Zhijie Shen.
svn merge --ignore-ancestry -c 1529682 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1529683 13f79535-47bb-0310-9956-ffa450edef68