#448268 by dww: Fix typo preventing update status cache from being cleared on theme admin page.

modules/update/update.module

@@ -293,7 +293,7 @@ function update_cron() {
  *
  * @see _update_cache_clear()
  */
-function update_form_system_themes_alter(&$form, $form_state) {
+function update_form_system_themes_form_alter(&$form, $form_state) {
   $form['#submit'][] = 'update_cache_clear_submit';
 }