$ git clone -n https://src.fedoraproject.org/rpms/R-ggplot2.git /var/lib/mock/f40-build-1944417-25177/root/chroot_tmpdir/scmroot/R-ggplot2
Cloning into '/var/lib/mock/f40-build-1944417-25177/root/chroot_tmpdir/scmroot/R-ggplot2'...
$ git fetch origin 62c26039104404426172e2ee7348cd6ebf90c803:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-ggplot2
 * [new ref]         62c26039104404426172e2ee7348cd6ebf90c803 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62c2603 Update to latest version