HADOOP-9760. Merge 1505875 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1505876 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4974. Merge 1505911 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1505912 13f79535-47bb-0310-9956-ffa450edef68