HADOOP-9977. Merging change r1525658 from branch-2 to branch-2.1-beta

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1525660 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5139. Merge r1525661 from branch-2 to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1525662 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5139. Merge r1525667 from branch-2 to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1525668 13f79535-47bb-0310-9956-ffa450edef68