YARN-1785. FairScheduler treats app lookup failures as ERRORs. (bc Wong via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1574605 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5167. Merge change r1574603 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1574608 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6043. Merging change r1574616 from trunk

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HDFS-6044. Merging change r1574622 from trunk

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Merge r1574623 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1574625 13f79535-47bb-0310-9956-ffa450edef68
YARN-1761. Modified RMAdmin CLI to check whether HA is enabled or not before it executes any of the HA admin related commands. Contributed by Xuan Gong.
svn merge --ignore-ancestry -c 1574661 ../../trunk/


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