Update CHANGES.txt for MAPREDUCE-4607 commit.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1383423 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -138,6 +138,9 @@ Release 2.0.3-alpha - Unreleased
 
   BUG FIXES
 
+    MAPREDUCE-4607. Race condition in ReduceTask completion can result in Task
+    being incorrectly failed. (Bikas Saha via tomwhite)
+
 Release 2.0.2-alpha - 2012-09-07 
 
   INCOMPATIBLE CHANGES