$ git clone -n https://src.fedoraproject.org/rpms/CImg.git /var/lib/mock/f45-build-39816-761/root/chroot_tmpdir/scmroot/CImg
Cloning into '/var/lib/mock/f45-build-39816-761/root/chroot_tmpdir/scmroot/CImg'...
$ git fetch origin 22dd27d2b78b1d3fd0f17d5bc4ca62cb2018acf5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/CImg
 * [new ref]         22dd27d2b78b1d3fd0f17d5bc4ca62cb2018acf5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 22dd27d build inside side-tag