$ git clone -n https://src.fedoraproject.org/rpms/R-tidyr.git /var/lib/mock/f40-build-1930468-25111/root/chroot_tmpdir/scmroot/R-tidyr
Cloning into '/var/lib/mock/f40-build-1930468-25111/root/chroot_tmpdir/scmroot/R-tidyr'...
$ git fetch origin 4c8760b4c43dd2b8cf1b47e95a945bd33eed2304:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-tidyr
 * [new ref]         4c8760b4c43dd2b8cf1b47e95a945bd33eed2304 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4c8760b R-maint-sig mass rebuild