Merge pull request cypht-org#1179 from Baraka24/warn_for_unsaved_chan…

…ges-once-set-cannot-be-unset

[FIX]Site Settings/General/:Warn for Unsaved Changes parameter once set cannot be unset

modules/core/handler_modules.php

@@ -974,7 +974,7 @@ public function process() {
         function warn_for_unsaved_changes_callback($val) {
             return $val;
         }
-        process_site_setting('warn_for_unsaved_changes', $this, 'warn_for_unsaved_changes_callback');
+        process_site_setting('warn_for_unsaved_changes', $this, 'warn_for_unsaved_changes_callback', false, true);
     }
 }