$ git clone -n https://src.fedoraproject.org/rpms/CImg.git /var/lib/mock/f42-build-3358872-45031/root/chroot_tmpdir/scmroot/CImg
Cloning into '/var/lib/mock/f42-build-3358872-45031/root/chroot_tmpdir/scmroot/CImg'...
$ git fetch origin 704d8e3b5ac42ed878143954d9bd0ec0e1575520:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/CImg
 * [new ref]         704d8e3b5ac42ed878143954d9bd0ec0e1575520 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 704d8e3 bump version