fix: improve wantsurl handling from loginpage list

Author: Peterburnett

login.php

@@ -37,6 +37,11 @@
 if ($wantsurl !== '') {
     // This is later used in core_login_get_return_url().
     $SESSION->wantsurl = (new moodle_url($wantsurl))->out(false);
+} else {
+    $wantsurl = optional_param('wants', '', PARAM_LOCALURL);
+    if ($wantsurl !== '') {
+        $SESSION->wantsurl = (new moodle_url($wantsurl))->out(false);
+    }
 }
 
 // Crap for hash anchor handling.