$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gtk3.git /var/lib/mock/f40-build-772752-126626/root/chroot_tmpdir/scmroot/rubygem-gtk3
Cloning into '/var/lib/mock/f40-build-772752-126626/root/chroot_tmpdir/scmroot/rubygem-gtk3'...
$ git fetch origin 10807d1f6e3b7b2f7b38e48681a54a631f0c0265:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gtk3
 * [new ref]         10807d1f6e3b7b2f7b38e48681a54a631f0c0265 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 10807d1 Rebuild for https://fedoraproject.org/wiki/Changes/Ruby_3.3