HDFS-6276. Merge r1589586 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589588 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5846. Rumen doesn't understand JobQueueChangedEvent (Nathan Roberts via raviprak)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589597 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6278. Merge r1589613 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589616 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6279. Merge r1589618 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1589619 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5693. Merge r1589620 from trunk.

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