MAPREDUCE-5815. Fixed test-failure of TestMRAppMaster by making MRAppMaster gracefully handle empty-queue names. Contributed by Akira Ajisaka.
svn merge --ignore-ancestry -c 1586559 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1586560 13f79535-47bb-0310-9956-ffa450edef68