$ git clone -n https://src.fedoraproject.org/rpms/rubygem-json.git /var/lib/mock/f40-build-2033879-47849/root/chroot_tmpdir/scmroot/rubygem-json
Cloning into '/var/lib/mock/f40-build-2033879-47849/root/chroot_tmpdir/scmroot/rubygem-json'...
$ git fetch origin 8b31707258da5a6b7c0fd9febd0c4704a89399aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-json
 * [new ref]         8b31707258da5a6b7c0fd9febd0c4704a89399aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8b31707 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild