$ git clone -n https://src.fedoraproject.org/rpms/darcs.git /var/lib/mock/f38-build-side-42-init-devel-1117845-30186/root/chroot_tmpdir/scmroot/darcs
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1117845-30186/root/chroot_tmpdir/scmroot/darcs'...
$ git fetch origin cae01b87c53f24f0a35a033aea9bc990d071718e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/darcs
 * [new ref]         cae01b87c53f24f0a35a033aea9bc990d071718e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cae01b8 bump release