When calling ssl.get_server_certificate() with a bad port number (I used 80 when I should have been using 443), the error raised is a bit misleading:

    >>> import ssl
    >>> ssl.get_server_certificate(('gitlab.com',80))
    [...]
    SSLError: [SSL: WRONG_VERSION_NUMBER] wrong version number (_ssl.c:847)

"SSL: wrong version number" seems to indicate that there is a mismatch between SSL versions supported by the client and the ones supported by the server. When here I guess the problem would better be described as "there is no SSL available at this address+port".

Note this is just the error that OpenSSL produces. There isn't a whole Python can do to change it.

I would still validate the error somewhere, maybe before reaching the OpenSSL library, because that same error is also shown for other cases. E.g:

http_connection = HTTPSConnection("localhost")
http_connection.request("POST", my_url, my_body, my_headers)

The use of an HTTPS connection for localhost effectively produces the same "SSL: WRONG VERSION NUMBER" error.

There is no easy fix for that. The TLS handskae is performed by OpenSSL internally. You could open a feature request with OpenSSL and ask them to implement better error detection and reporting.