Index: modules/node/content_types.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/content_types.inc,v
retrieving revision 1.47
diff -u -p -r1.47 content_types.inc
--- modules/node/content_types.inc	28 Nov 2007 10:29:20 -0000	1.47
+++ modules/node/content_types.inc	16 Dec 2007 19:13:30 -0000
@@ -299,19 +299,20 @@ function node_type_form_submit($form, &$
 
   // Save or reset persistent variable values.
   foreach ($variables as $key => $value) {
-    $key .= '_'. $type->type;
+    $variable_new = $key .'_'. $type->type;
+    $variable_old = $key .'_'. $type->old_type;
+
     if ($op == t('Reset to defaults')) {
-      variable_del($key);
+      variable_del($variable_old);
     }
     else {
       if (is_array($value)) {
         $value = array_keys(array_filter($value));
       }
-      variable_set($key, $value);
+      variable_set($variable_new, $value);
 
-      if ($type->old_type != $type->type) {
-        $key = str_replace($type->type, $type->old_type, $key);
-        variable_del($key);
+      if ($variable_new != $variable_old) {
+        variable_del($variable_old);
       }
     }
   }