$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rack.git /var/lib/mock/f40-build-2323284-58705/root/chroot_tmpdir/scmroot/rubygem-rack
Cloning into '/var/lib/mock/f40-build-2323284-58705/root/chroot_tmpdir/scmroot/rubygem-rack'...
$ git fetch origin 900f9e8dc9c46307fe55662458af9cceeabddf79:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rack
 * [new ref]         900f9e8dc9c46307fe55662458af9cceeabddf79 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 900f9e8 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild