HDFS-4461.  DirectoryScanner: volume prefix takes up memory for every block that is scanned (Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494403 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5194. Heed interrupts during Fetcher shutdown.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494417 13f79535-47bb-0310-9956-ffa450edef68
Cleanup CHANGES.txt for 2.1.0-beta section and make it consistent with trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494430 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4917. Merge 1494433 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494434 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4917. Revert r1494434 previous merge that included extraneous change.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494442 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4917. Merge 1494433 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494446 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-HADOOP-9166-branch-2-gd