YARN-1866. Fixed an issue with renewal of RM-delegation tokens on restart or fail-over. Contributed by Jian He.
svn merge --ignore-ancestry -c 1581448 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1581450 13f79535-47bb-0310-9956-ffa450edef68