HDFS-9696. Garbage snapshot records linger forever. Adding an entry to CHANGES.txt.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -253,6 +253,8 @@ Release 2.7.3 - UNRELEASED
     HDFS-10623. Remove unused import of httpclient.HttpConnection from
     TestWebHdfsTokens. (Hanish Koneru via Arpit Agarwal)
 
+    HDFS-9696. Garbage snapshot records linger forever. (kihwal)
+
 Release 2.7.2 - 2016-01-25
 
   INCOMPATIBLE CHANGES