$ git clone -n https://src.fedoraproject.org/rpms/R-sandwich.git /var/lib/mock/f45-build-6395-348/root/chroot_tmpdir/scmroot/R-sandwich
Cloning into '/var/lib/mock/f45-build-6395-348/root/chroot_tmpdir/scmroot/R-sandwich'...
$ git fetch origin 8512a17d04f2f42df8389ef8766cdc3c21f3b41a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-sandwich
 * [new ref]         8512a17d04f2f42df8389ef8766cdc3c21f3b41a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8512a17 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild