HDFS-4053. Merging change r1399908 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1475848 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1475959 from trunk for HADOOP-9503. Remove sleep between IPC client connect timeouts.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1475960 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4434. Reverting the merge to branch-2

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1475972 13f79535-47bb-0310-9956-ffa450edef68