HDFS-4544. Error in deleting blocks should not do check disk, for all types of errors. Contributed by Arpit Agarwal.

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HADOOP-9375. Port HADOOP-7290 to branch-1 to fix TestUserGroupInformation failure. Contributed by Xiaobo Peng.

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HDFS-4551. When copying bytes in DatanodeWebHdfsMethods OPEN, use 4096 buffer size to improve performance.  Contributed by Mark Wagner


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Move HDFS-4252 to 1.2.0 in CHANGES.txt.


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