$ git clone -n https://src.fedoraproject.org/rpms/rubygem-racc.git /var/lib/mock/f40-build-772494-126420/root/chroot_tmpdir/scmroot/rubygem-racc
Cloning into '/var/lib/mock/f40-build-772494-126420/root/chroot_tmpdir/scmroot/rubygem-racc'...
$ git fetch origin 12fb1d107657cbb892d5b5a6223d2bf03a13292c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-racc
 * [new ref]         12fb1d107657cbb892d5b5a6223d2bf03a13292c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 12fb1d1 Rebuild for https://fedoraproject.org/wiki/Changes/Ruby_3.3