Merge r1616302 from trunk. YARN-2374. Fixed TestDistributedShell#testDSShell failure due to hostname dismatch. Contributed by Varun Vasudev

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1616305 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6791. Merge change r1616306 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1616311 13f79535-47bb-0310-9956-ffa450edef68