svn merge -c 1429040 FIXES: MAPREDUCE-4832. MR AM can get in a split brain situation. Contributed by Jason Lowe


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1429049 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'branch-0.23' of github.com:griddynamics/yhadoop-common into branch-0.23-gd
Merge branch 'branch-0.23-gd' of github.com:griddynamics/yhadoop-common into fb-xxx-hadoop-auth-kerberos-realm-branch-0.23-gd