MAPREDUCE-4278. Cannot run two local jobs in parallel from the same gateway. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1430363 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9119. Add test to FileSystemContractBaseTest to verify integrity of overwritten files. Contributed by Steve Loughran.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1430387 13f79535-47bb-0310-9956-ffa450edef68