$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gtk2.git /var/lib/mock/f42-build-865338-173025/root/chroot_tmpdir/scmroot/rubygem-gtk2
Cloning into '/var/lib/mock/f42-build-865338-173025/root/chroot_tmpdir/scmroot/rubygem-gtk2'...
$ git fetch origin abd6b2a2a252311500d9b1ee206b6285949f623d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gtk2
 * [new ref]         abd6b2a2a252311500d9b1ee206b6285949f623d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at abd6b2a Rebuild for https://fedoraproject.org/wiki/Changes/Ruby_3.4