$ git clone -n https://src.fedoraproject.org/rpms/R-futile.options.git /var/lib/mock/f43-build-58895239-6569073/root/chroot_tmpdir/scmroot/R-futile.options
Cloning into '/var/lib/mock/f43-build-58895239-6569073/root/chroot_tmpdir/scmroot/R-futile.options'...
$ git fetch origin e4a43b256f323f3c9963f74ad272384283d35148:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-futile.options
 * [new ref]         e4a43b256f323f3c9963f74ad272384283d35148 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4a43b2 R-maint-sig mass rebuild