HDFS-6478. RemoteException can't be retried properly for non-HA scenario. Contributed by Ming Ma.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1611410 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10732. Fix locking in credential update. (Ted Yu via omalley)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1611415 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10733. Fix potential null dereference in CredShell. (Ted Yu via
omalley)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1611419 13f79535-47bb-0310-9956-ffa450edef68