Fix typo (HDFS-5276 -> HDFS-5267) in CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1531503 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -14,7 +14,7 @@ Release 2.3.0 - UNRELEASED
 
   IMPROVEMENTS
 
-    HDFS-5276. Remove volatile from LightWeightHashSet. (Junping Du via llu)
+    HDFS-5267. Remove volatile from LightWeightHashSet. (Junping Du via llu)
 
     HDFS-4657.  Limit the number of blocks logged by the NN after a block
     report to a configurable value.  (Aaron T. Myers via Colin Patrick