FYI, I have just made the necessary updates to bring the OpenSSL master
branch up to TLSv1.3 draft-20 compatibility. I don't know of any other
draft-20 implementations yet so treat with caution and please test!
As with all new drafts, draft-20 is not compatible with draft-19. If you
were using the previous draft-19 code (or the draft-18 code) then you
could encounter issues.
I will ask Richard to create a new tls1.3-draft-19 branch for those that
want to stick with the previous version for now.