HDFS-6878: Merging r1619271 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619272 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6758: Merging r1619275 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619276 13f79535-47bb-0310-9956-ffa450edef68