Update CHANGES.txt for commit 1198910.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1198912 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -81,6 +81,9 @@ Release 0.23.1 - Unreleased
     MAPREDUCE-3291. App fail to launch due to delegation token not 
     found in cache (Robert Evans via mahadev)
 
+    MAPREDUCE-3344. o.a.h.mapreduce.Reducer since 0.21 blindly casts to
+    ReduceContext.ValueIterator. (Brock Noland via tomwhite)
+
 Release 0.23.0 - 2011-11-01 
 
   INCOMPATIBLE CHANGES