Fix bug closure for “dpkg-deb: Do not warn on strange timestamps”

Spotted-by: Carl Fürstenberg <azatoth@gmail.com>

debian/changelog

@@ -210,7 +210,7 @@ dpkg (1.16.1) UNRELEASED; urgency=low
   * Fix double “error:” string in dpkg missing PATH error output.
     Closes: #639997
   * Do not warn on strange timestamps when unpacking with dpkg-deb.
-    Closes: #639997
+    Closes: #640298
   * Reduce dpkg-trigger binary size by refactoring libdpkg modules so that
     it does not end up pulling triglib.
   * Reduce dpkg-deb binary size by refectoring libdpkg modules so that it