$ git clone -n https://src.fedoraproject.org/rpms/guile-reader.git /var/lib/mock/f45-build-13240-447/root/chroot_tmpdir/scmroot/guile-reader
Cloning into '/var/lib/mock/f45-build-13240-447/root/chroot_tmpdir/scmroot/guile-reader'...
$ git fetch origin c7224ed18526c47b2455921abc663163333e18a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/guile-reader
 * [new ref]         c7224ed18526c47b2455921abc663163333e18a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c7224ed Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild