YARN-325. RM CapacityScheduler can deadlock when getQueueInfo() is called and a container is completing (Arun C Murthy via tgraves)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1431071 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1431131 FIXES: MAPREDUCE-4848. TaskAttemptContext cast error during AM recovery. Contributed by Jerry Chen


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1431137 13f79535-47bb-0310-9956-ffa450edef68