TLS 1.2 has one-way close notify. For example typical HTTP clients like curl send a close_notify and then shut down the TCP connection. HTTP servers may not reply with close_notify or may not wait for the client to confirm the server-side close notify.

Python's ssl module does not support one-way close yet. It's an unfortunate limitation of the API that predates my involvement in the ssl module. The unwrap() methods always performs a blocking two-way shutdown. unwrap() calls SSL_shutdown() twice to downgrade a TLS connection to a plain TCP connection. The unwrap() API also requires cooperation from both parties.

https://tools.ietf.org/html/rfc5246#section-7.2.1
https://www.openssl.org/docs/manmaster/man3/SSL_shutdown.html