I'm doing an implementation of the NTS protocol for my customer Netnod:

https://github.com/Netnod/nts-poc-python

NTS is draft RFC on its way to become a standard:

https://datatracker.ietf.org/doc/draft-ietf-ntp-using-nts-for-ntp/

NTS requires the export_keying_material functionality as described in RFC5705.

Basically it's a part of the TLS standard, is used by 10 existing protocols with more on the way.  And I can't implement a NTS key establishment server or client without the function.  That's why I added the functionality and verified that it works both with the stable 3.7.4 release and with the master branch of the cpython repository.

I tested with 3.7.4 first on my machine because that's the release of Python that comes with Ubuntu and I wanted to have as few differences as as possible compared to the distribution version.  I then forward ported the patch to the master branch and verified that my NTS implementation still works with that branch.