make BlockingPortal.stop sync

src/anyio/from_thread.py

@@ -143,7 +143,7 @@ async def sleep_until_stopped(self) -> None:
         """Sleep until :meth:`stop` is called."""
         await self._stop_event.wait()
 
-    async def stop(self, cancel_remaining: bool = False) -> None:
+    def stop(self, cancel_remaining: bool = False) -> DeprecatedAwaitable:
         """
         Signal the portal to shut down.
 
@@ -159,6 +159,8 @@ async def stop(self, cancel_remaining: bool = False) -> None:
         if cancel_remaining:
             self._task_group.cancel_scope.cancel()
 
+        return DeprecatedAwaitable(self.stop)
+
     async def _call_func(self, func: Callable, args: tuple, kwargs: Dict[str, Any],
                          future: Future) -> None:
         def callback(f: Future) -> None: