MAPREDUCE-5689. MRAppMaster does not preempt reducers when scheduled maps cannot be fulfilled. (lohit via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1555161 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5695. Clean up TestOfflineEditsViewer and OfflineEditsViewerHelper. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1555164 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5705. TestSecondaryNameNodeUpgrade#testChangeNsIDFails may fail due to ConcurrentModificationException. Contributed by Ted Yu

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1555190 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk