HDFS-6411. Merging change r1597895 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1597896 13f79535-47bb-0310-9956-ffa450edef68
YARN-2105. Fix TestFairScheduler after YARN-2012. (Ashwin Shankar via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1597903 13f79535-47bb-0310-9956-ffa450edef68