HDFS-3851. Merging change r1377372 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1609857 13f79535-47bb-0310-9956-ffa450edef68
HDFS-3851. Merging change r1609858 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1609859 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'branch-2' into HDFS-2856-branch-2

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java