Comment 14 for bug 1526413

Victor, your issue is unrelated to this one. This issue was caused by errors with validating host names when using IPv6 addresses, which can only manifest itself by host name validation errors. The error you're seeing is caused by the server aborting the TLS handshake, likely because of an incompatibility in client and server settings.

There is no reason to blame this on requests 2.9.1 as far as I can see.