$ git clone -n https://src.fedoraproject.org/rpms/R-sciplot.git /var/lib/mock/f42-build-side-1-3501326-45974/root/chroot_tmpdir/scmroot/R-sciplot
Cloning into '/var/lib/mock/f42-build-side-1-3501326-45974/root/chroot_tmpdir/scmroot/R-sciplot'...
$ git fetch origin 6c7739ffa801a05ff5f787d7fcf3ca9037b3061c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-sciplot
 * [new ref]         6c7739ffa801a05ff5f787d7fcf3ca9037b3061c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6c7739f R-maint-sig mass rebuild