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
HDFS-4249: refactor NameNode#validateConfigurationSettings
Merge branch 'trunk' into HDFS-4249