I've rebuilt the relevant reverse-build-dependencies from unstable
In addition to the packages mentioned here, it seems there is another package involved: golang-gopkg-libgit2-git2go.v28 . It only builds arch-all packages and does not directly depend on the library, but it FTBFS and it's autopkgtest fails with the new version. The FTBFS was picked up in a rebuild test by Lucas and a bug report was filed https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=976522