$ git clone -n https://src.fedoraproject.org/rpms/foobillard.git /var/lib/mock/f42-build-3275497-41321/root/chroot_tmpdir/scmroot/foobillard
Cloning into '/var/lib/mock/f42-build-3275497-41321/root/chroot_tmpdir/scmroot/foobillard'...
$ git fetch origin 07daff24b64492d0c05fde26a6809b04a728dabc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/foobillard
 * [new ref]         07daff24b64492d0c05fde26a6809b04a728dabc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 07daff2 Fix FTBFS