HADOOP-9352. Expose UGI.setLoginUser for tests (daryn)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1452338 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5043. Fetch failure processing can cause AM event queue to backup and eventually OOM (Jason Lowe via bobby)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1452372 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails in the middle (kihwal via daryn)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1452384 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd