$ git clone -n https://src.fedoraproject.org/rpms/R-unitizer.git /var/lib/mock/f40-build-1930460-25111/root/chroot_tmpdir/scmroot/R-unitizer
Cloning into '/var/lib/mock/f40-build-1930460-25111/root/chroot_tmpdir/scmroot/R-unitizer'...
$ git fetch origin 1c01f10bb641bcbdc0fcd224cef043c37d7962f3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-unitizer
 * [new ref]         1c01f10bb641bcbdc0fcd224cef043c37d7962f3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1c01f10 R-maint-sig mass rebuild