YARN-1094. Fixed a blocker with RM restart code because of which RM crashes when try to recover an existing app. Contributed by Vinod Kumar Vavilapalli.
svn merge --ignore-ancestry -c 1517215 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1517216 13f79535-47bb-0310-9956-ffa450edef68