I am trying to use SSLContext.set_servername_callback in my program but when a callback is set, it seems that connecting to the server without providing a server name causes a segmentation fault. (e.g. 'openssl s_client -connect localhost:443 -servername foo' is OK but 'openssl s_client -connect localhost:443' crashes the server. A simple test that causes the same error is included in the patch.)

My expectation was to get None as the second argument of the callback in such cases so I modified Modules/_ssl.c (as in the patch) to make it behave as I expected.

The modification seems to work fine as far as I've tested, but I'd appreciate if an official fix is available.