Merge -r 1441474:1441475 from trunk to branch-2. Fixes: HADOOP-9124. SortedMapWritable violates contract of Map interface for equals() and hashCode(). Contributed by Surenkumar Nihalani

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1441476 13f79535-47bb-0310-9956-ffa450edef68