HADOOP-10831. UserProvider is not thread safe. (Benoy Antony via umamahesh)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610789 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5809. BlockPoolSliceScanner and high speed hdfs appending make datanode to drop into infinite loop (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610790 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10834. Typo in CredentialShell usage. (Benoy Antony via umamahesh)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610794 13f79535-47bb-0310-9956-ffa450edef68