[entities, view] delete dead code The auto_unwrap_bw_compat metaclass calls unwrap_adapter_compat, which was removed in changeset 697a8181ba30 "remove 3.9 bw compat". So this can't possibly work anymore, meaning we can get rid of it.

if repo.system_source.dbdriver == 'postgres':
    sql('ALTER TABLE appears ADD COLUMN weight float')
    sql('UPDATE appears SET weight=1.0 ')