$ git clone -n https://src.fedoraproject.org/rpms/darcs.git /var/lib/mock/f41-build-side-1-2935631-35250/root/chroot_tmpdir/scmroot/darcs
Cloning into '/var/lib/mock/f41-build-side-1-2935631-35250/root/chroot_tmpdir/scmroot/darcs'...
$ git fetch origin 8bf8dc7dbad2399426f047cdbe22f72669ef961e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/darcs
 * [new ref]         8bf8dc7dbad2399426f047cdbe22f72669ef961e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8bf8dc7 update to 2.18.2 and enable threading on all archs