HDFS-4340. Merge r1443169 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1471692 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4340. Merge r1448502 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1471698 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4434. Merge r1469644 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1471703 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-YAHOO-258-branch-2-gd