merge YARN-737 from trunk. Throw some specific exceptions directly instead of wrapping them in YarnException. Contributed by Jian He.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1491897 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1491914 FIXES: MAPREDUCE-5315.  DistCp reports success even on failure. (mithun and jlowe via daryn)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1491918 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-MAPREDUCE-4884-branch-2-gd