svn merge -c 1547393 merging from trunk to branch-2 to fix: HDFS-5558. LeaseManager monitor thread can crash if the last block is complete but another block is not.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1547395 13f79535-47bb-0310-9956-ffa450edef68