HDFS-7165. Separate block metrics for files with replication count 1. Contributed by Zhe Zhang.
HADOOP-11250. fix endmacro of set_find_shared_library_without_version in CMakeLists (Yi Liu via Colin P. McCabe)
(cherry picked from commit e488f0d93bf22d25aaaac7a6a88fc300f9aa6d5a)
HDFS-7230. Add rolling downgrade documentation. Contributed by Tsz Wo Nicholas Sze.

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
HADOOP-11221. IdentityHashStore assumes System.identityHashCode() is non-negative. Contributed by Jinghui Wang
HDFS-3342. SocketTimeoutException in BlockSender.sendChunks could have a better error message. Contributed by Yongjun Zhang.

(cherry picked from commit 16c0f04c50822a39610e34e0715d3d4a44be5a5f)
update CHANGES.txt to move HADOOP-11247 to 2.6