[yjftsjthsd-h]

It appears that git currently has experimental, non-backward-compatible support for sha256, so I'd guess "as soon as they finish fixing any issues and figure out a nice upgrade path", with the caveat that there's little pressure because it's not actually a practical problem yet and isn't expected to be one in the foreseeable future.

[wyoung2]

Fossil's method is backwards-compatible, and we published the method for it five years ago (2017-03-05): https://fossil-scm.org/home/doc/trunk/www/hashpolicy.wiki