svn merge -c 1503972 merging to branch-2.1 to fix HDFS-4998

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1503974 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1503976 merging to branch-2 to fix HADOOP-9738. TestDistCh fails. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1503978 13f79535-47bb-0310-9956-ffa450edef68
YARN-62. Modified NodeManagers to avoid AMs from abusing container tokens for repetitive container launches. Contributed by Omkar Vinit Joshi.
svn merge --ignore-ancestry -c 1503986 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1503988 13f79535-47bb-0310-9956-ffa450edef68