MAPREDUCE-5827. Merging change r1589223 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589236 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5827. Merging change r1589238 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589241 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5833. TestRMContainerAllocator fails ocassionally. Contributed by Zhijie Shen.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589259 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10503. Merging change r1589273 from trunk to branch-2.

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