$ git clone -n https://src.fedoraproject.org/rpms/R-lokern.git /var/lib/mock/f43-build-58895860-6569073/root/chroot_tmpdir/scmroot/R-lokern
Cloning into '/var/lib/mock/f43-build-58895860-6569073/root/chroot_tmpdir/scmroot/R-lokern'...
$ git fetch origin 75b295bd05101df7ff50b40224cbe8d63b24cff8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lokern
 * [new ref]         75b295bd05101df7ff50b40224cbe8d63b24cff8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 75b295b R-maint-sig mass rebuild