HADOOP-8562. Merge r1477376 for HADOOP-9413, r1476877 for HDFS-4734, r1476856 for HADOOP-9524.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1486238 13f79535-47bb-0310-9956-ffa450edef68