HDFS-4762,HDFS-4948. Merging change r1499190 from branch-2

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1499199 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5357. Merging change r1499217 from branch-2 to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1499218 13f79535-47bb-0310-9956-ffa450edef68