svn merge -c 1478517 from branch-1 for HDFS-4774. Backport HDFS-4525: Provide an API for knowing whether a file is closed.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2@1478518 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1478524 from branch-1 for HADOOP-9543. TestFsShellReturnCode may fail if the hardcoded user "admin" is not a valid user in the loacl OS.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2@1478525 13f79535-47bb-0310-9956-ffa450edef68