YARN-1640. Fixed manual failover of ResourceManagers to work correctly in secure clusters. Contributed by Xuan Gong.
svn merge --ignore-ancestry -c 1579510 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.4@1579512 13f79535-47bb-0310-9956-ffa450edef68