If `read()` in the ConnectionHandler thread raises `OSError` (except `ConnectionError`), the ConnectionHandler shuts down the entire ThreadedEchoServer, preventing further connections. It also does that for `EPROTOTYPE` in `wrap_conn`. As far as I can see, this is done to avoid the server thread getting stuck, forgotten, in its accept loop. However, since 2011 (5b95eb90a7167285b6544b50865227c584943c9a) the server is used as a context manager, and its `__exit__` does `stop()` and `join()`. (I'm not sure if we *always* used `with` since that commit, but currently we do.) Make sure that the context manager *is* used, and remove the `server.stop()` calls from ConnectionHandler.