Updated CHANGES.txt to move HADOOP-12526 to 2.6.3.

(cherry picked from commit f6cecbfce586c4870d0f6b54b9bca2a30af7b9fa)

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -18,8 +18,6 @@ Release 2.7.3 - UNRELEASED
     HADOOP-12296. when setnetgrent returns 0 in linux, exception should be
     thrown (Chang Li via jlowe)
 
-    HADOOP-12526. there are duplicate dependency definitions in pom's (sjlee)
-
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES
@@ -832,6 +830,8 @@ Release 2.6.3 - UNRELEASED
 
   BUG FIXES
 
+    HADOOP-12526. there are duplicate dependency definitions in pom's (sjlee)
+
 Release 2.6.2 - 2015-10-28
 
   INCOMPATIBLE CHANGES