Merge -r 723917:723918 from trunk to move the change log of HADOOP-4742 into branch 0.18

git-svn-id: https://svn.apache.org/repos/asf/hadoop/core/branches/branch-0.18@723928 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -81,6 +81,8 @@ Release 0.18.3 - Unreleased
     HADOOP-4778. Check for zero size block meta file when updating a block.
     (szetszwo)
 
+    HADOOP-4742. Replica gets deleted by mistake. (Wang Xu via hairong)
+
 Release 0.18.2 - 2008-11-03
 
   BUG FIXES