trigger transfer progress -1 if download is canceled

oml/item/api.py

@@ -325,6 +325,9 @@ def cancelDownloads(data):
             for l in item.lists.filter_by(user_id=settings.USER_ID):
                 l.items.remove(item)
             item.update()
+            trigger_event('transfer', {
+                'id': item.id, 'progress': -1
+            })
         response = {'cancelled': ids}
     return response
 actions.register(cancelDownloads, cache=False)