$ git clone -n https://src.fedoraproject.org/rpms/darcs.git /var/lib/mock/f39-build-1825594-41864/root/chroot_tmpdir/scmroot/darcs
Cloning into '/var/lib/mock/f39-build-1825594-41864/root/chroot_tmpdir/scmroot/darcs'...
$ git fetch origin 5718fc6962743a1593cb5ce155934fd0923f14fa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/darcs
 * [new ref]         5718fc6962743a1593cb5ce155934fd0923f14fa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5718fc6 bump upperbounds