Fixing wrong jira number from HDFS-7509 to HDFS-7745.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security@1183133 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -38,7 +38,7 @@ Release 0.20.206.0 - unreleased
     HADOOP-7509. Improve exception message thrown when Authentication is 
     required. (Ravi Prakash via suresh)
 
-    HADOOP-7509. Fix wrong variable name in exception message introduced
+    HADOOP-7745. Fix wrong variable name in exception message introduced
     in HADOOP-7509. (Ravi Prakash via suresh)
 
 Release 0.20.205.1 - unreleased