Python 2.7.9+ and 3.4+ support configuring CRL verification on the SSLContext object.

https://docs.python.org/2/library/ssl.html#ssl.SSLContext.verify_flags

Add a new option, ssl_crlfile, the path to the user's crl.pem. If provided, and the SSLContext.verify_flags attribute exists, load crl.pem using SSLContext.load_verify_locations and set SSLContext.verify_flags to VERIFY_CRL_CHECK_LEAF (to match the server).

https://docs.python.org/2/library/ssl.html#ssl.VERIFY_CRL_CHECK_LEAF