HDFS-4852. Merging change r1619967 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619968 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6899: Merging r1619970 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619971 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6899. Undo merge of r1619971

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619972 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6899: Merging r1619970 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619973 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6899. Undo merge of r1619973

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619974 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6899: Merging r1619970 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619975 13f79535-47bb-0310-9956-ffa450edef68