$ git clone -n https://src.fedoraproject.org/rpms/R-fortunes.git /var/lib/mock/f42-build-side-1-3499413-45965/root/chroot_tmpdir/scmroot/R-fortunes
Cloning into '/var/lib/mock/f42-build-side-1-3499413-45965/root/chroot_tmpdir/scmroot/R-fortunes'...
$ git fetch origin 80c5c914e1feec7f5e519483e294a606e2da45aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-fortunes
 * [new ref]         80c5c914e1feec7f5e519483e294a606e2da45aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 80c5c91 R-maint-sig mass rebuild