MAPREDUCE-5075. DistCp leaks input file handles since ThrottledInputStream does not close the wrapped InputStream.  (Chris Nauroth via tgraves)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1461305 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-0.23' into branch-0.23-gd
Merge remote branch 'origin/branch-0.23-gd' into fb-HADOOP-9078-branch-0.23-gd