$ git clone -n https://src.fedoraproject.org/rpms/gears-backgrounds.git /var/lib/mock/f45-build-9722-408/root/chroot_tmpdir/scmroot/gears-backgrounds
Cloning into '/var/lib/mock/f45-build-9722-408/root/chroot_tmpdir/scmroot/gears-backgrounds'...
$ git fetch origin 3766150dfd7b529b21cb7ef3c906b439fd255907:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gears-backgrounds
 * [new ref]         3766150dfd7b529b21cb7ef3c906b439fd255907 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3766150 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild