Clarify a misleading operation

Author: Davnit

src/controllers/Packet/Edit.php

@@ -139,11 +139,13 @@ protected function handlePost(Router &$router, PacketEditModel &$model) {
       $model->packet->setEditedDateTime(
         new DateTime("now", new DateTimeZone("Etc/UTC"))
       );
-      
-      $model->packet->setUsedBy($used_by);
 
       $success = $model->packet->update();
 
+      // Used-by is stored in a different table than packet data so it is
+      // updated separately.
+      $model->packet->setUsedBy($used_by);
+
     } catch (QueryException $e) {
 
       // SQL error occurred. We can show a friendly message to the user while