YARN-1928. Fixed a race condition in TestAMRMRPCNodeUpdates which caused it to fail occassionally. Contributed by Zhijie Shen.
svn merge --ignore-ancestry -c 1587114 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.4@1587116 13f79535-47bb-0310-9956-ffa450edef68