svn merge -c 1452384 FIXES: 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/branches/branch-2@1452388 13f79535-47bb-0310-9956-ffa450edef68