HDFS-6340.DN can't finalize upgrade. (Contributed by Rahul Singhal)

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HDFS-6329. WebHdfs does not work if HA is enabled on NN but logical URI is not configured. Contributed by Kihwal Lee.

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Fix CHANGES.txt

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HDFS-6313. WebHdfs may use the wrong NN when configured for multiple HA NNs. Contributed by Kihwal Lee.

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