$ git clone -n https://src.fedoraproject.org/rpms/rubygem-json.git /var/lib/mock/f40-build-777948-129655/root/chroot_tmpdir/scmroot/rubygem-json
Cloning into '/var/lib/mock/f40-build-777948-129655/root/chroot_tmpdir/scmroot/rubygem-json'...
$ git fetch origin 77cc0128a8102647c25c90b84217d2a45c04aedb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-json
 * [new ref]         77cc0128a8102647c25c90b84217d2a45c04aedb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 77cc012 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild