MAPREDUCE-5585. TestCopyCommitter#testNoCommitAction Fails on JDK7 (jeagles)

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MAPREDUCE-5586. TestCopyMapper#testCopyFailOnBlockSizeDifference fails when run from hadoop-tools/hadoop-distcp directory (jeagles)

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HDFS-5346. Avoid unnecessary call to getNumLiveDataNodes() for each block during IBR processing. Contributed by Ravi Prakash.

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