fix: revert exception message

Author: ordinary-jamie

Lib/asyncio/base_events.py

@@ -344,7 +344,7 @@ def _start_serving(self):
         elif self._state == _ServerState.SERVING:
             return
         else:
-            raise RuntimeError(f'server {self!r} was already started and then closed')
+            raise RuntimeError('is closed')
 
         for sock in self._sockets:
             sock.listen(self._backlog)

Lib/test/test_asyncio/test_server.py

@@ -66,7 +66,7 @@ async def main(srv):
         self.assertIsNone(srv._waiters)
         self.assertFalse(srv.is_serving())
 
-        with self.assertRaisesRegex(RuntimeError, r'started and then closed'):
+        with self.assertRaisesRegex(RuntimeError, r'is closed'):
             self.loop.run_until_complete(srv.serve_forever())
 
 
@@ -119,7 +119,7 @@ async def main(srv):
             self.assertIsNone(srv._waiters)
             self.assertFalse(srv.is_serving())
 
-            with self.assertRaisesRegex(RuntimeError, r'started and then closed'):
+            with self.assertRaisesRegex(RuntimeError, r'is closed'):
                 self.loop.run_until_complete(srv.serve_forever())
 
 
@@ -215,7 +215,7 @@ async def serve(rd, wr):
         await asyncio.sleep(0)
         self.assertTrue(task.done())
 
-        with self.assertRaisesRegex(RuntimeError, r'started and then closed'):
+        with self.assertRaisesRegex(RuntimeError, r'is closed'):
             await srv.start_serving()
 
     async def test_abort_clients(self):