svn merge -c 1576151 from branch-2 for HDFS-6076. DataNode with SimulatedDataSet should not create DatanodeRegistration with namenode layout version and namenode node type.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.4@1576152 13f79535-47bb-0310-9956-ffa450edef68