Fix a typo in CHANGE.txt: MAPREDUCE-2723 should be MAPREDUCE-2732.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1151464 13f79535-47bb-0310-9956-ffa450edef68

mapreduce/CHANGES.txt

@@ -356,7 +356,7 @@ Trunk (unreleased changes)
     MAPREDUCE-2622. Remove the last remaining reference to the deprecated
     configuration "io.sort.mb". (Harsh J Chouraria via todd)
 
-    MAPREDUCE-2723. Remove directly accessing FSNamesystem.LOG from
+    MAPREDUCE-2732. Remove directly accessing FSNamesystem.LOG from
     TestCopyFiles and TestDistCh.  (szetszwo)
 
 Release 0.22.0 - Unreleased