MAPREDUCE-5488. Changed MR client to keep trying to reach the application when it sees that on attempt's AM is down. Contributed by Jian He.
svn merge --ignore-ancestry -c 1524856 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1524858 13f79535-47bb-0310-9956-ffa450edef68