Move the change log of HADOOP-3519 to release 0.18.0 section.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/core/trunk@669589 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -15,9 +15,6 @@ Trunk (unreleased changes)
     HADOOP-3563.  Refactor the distributed upgrade code so that it is 
     easier to identify datanode and namenode related code. (dhruba)
 
-    HADOOP-3576. Fix NullPointerException when renaming a directory
-    to its subdirectory. (Tse Wo (Nicholas), SZE via hairong) 
-
 Release 0.18.0 - Unreleased
 
   INCOMPATIBLE CHANGES
@@ -674,6 +671,9 @@ Release 0.17.1 - Unreleased
     HADOOP-1979. Speed up fsck by adding a buffered stream. (Lohit
     Vijaya Renu via omalley)
 
+    HADOOP-3576. Fix NullPointerException when renaming a directory
+    to its subdirectory. (Tse Wo (Nicholas), SZE via hairong)
+
 Release 0.17.0 - 2008-05-18
 
   INCOMPATIBLE CHANGES