HDFS-4372. Merging change r1502420 from branch-2.1-beta to branch-2.1.0-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1.0-beta@1502422 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4373. Merging change r1502424 from branch-2.1-beta to branch-2.1.0-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1.0-beta@1502425 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4374. Merging change r1502427 from branch-2.1-beta to branch-2.1.0-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1.0-beta@1502428 13f79535-47bb-0310-9956-ffa450edef68