$ git clone -n https://src.fedoraproject.org/rpms/R-curl.git /var/lib/mock/f40-build-1514340-23911/root/chroot_tmpdir/scmroot/R-curl
Cloning into '/var/lib/mock/f40-build-1514340-23911/root/chroot_tmpdir/scmroot/R-curl'...
$ git fetch origin a18a7bd940191eaf385052e848901a6f087f9da1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-curl
 * [new ref]         a18a7bd940191eaf385052e848901a6f087f9da1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a18a7bd Update to latest version