YARN-2400: Addendum fix for TestAMRestart failure. Contributed by Jian He


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1617334 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6837. Merge r1617337 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1617338 13f79535-47bb-0310-9956-ffa450edef68