Add additional bug closures

debian/changelog

@@ -1,7 +1,7 @@
 dpkg (1.15.5) UNRELEASED; urgency=low
 
   [ Guillem Jover ]
-  * Remove obsolete conffiles on purge. Closes: #454628
+  * Remove obsolete conffiles on purge. Closes: #421367, #453005, #454628
 
   [ Updated dpkg translations ]
   * German (Sven Joachim).