Add an entry of YARN-4312 to CHANGES.txt

hadoop-yarn-project/CHANGES.txt

@@ -1147,6 +1147,9 @@ Release 2.7.2 - UNRELEASED
     YARN-3580. [JDK8] TestClientRMService.testGetLabelsToNodes fails. (Robert Kanter
     via junping_du)
 
+    YARN-4312. TestSubmitApplicationWithRMHA fails on branch-2.7 and branch-2.6
+    as some of the test cases time out. (Varun Saxena via ozawa)
+
 Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES