Can't use app_or_default for __reduce__ after all, as need to pass state to child processes on Windows

celery/app/__init__.py

@@ -129,8 +129,6 @@ class App(base.BaseApp):
             return inner_create_task_cls()(*args)
         return inner_create_task_cls(**options)
 
-    def __reduce__(self):
-        return (app_or_default, ())
 
 #: The "default" loader is the default loader used by old applications.
 default_loader = os.environ.get("CELERY_LOADER") or "default"