HADOOP-7851. Moving to 0.23.1 section in CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1241724 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -126,6 +126,9 @@ Release 0.23.1 - Unreleased
 
    HADOOP-7841. Run tests with non-secure random. (tlipcon)
 
+    HADOOP-7851. Configuration.getClasses() never returns the default value. 
+                 (Uma Maheswara Rao G via amarrk)
+
    HADOOP-7787. Make source tarball use conventional name.
    (Bruno Mahé via tomwhite)