switch cfg.Version {
	case "29":
		// V29 -> V30
		cfg.Compression.Enabled = false
		cfg.Compression.Extensions = strings.Split(compress.DefaultExtensions, config.ValueSeparator)
		cfg.Compression.MimeTypes = strings.Split(compress.DefaultMimeTypes, config.ValueSeparator)
	case "30":
		// V30 -> V31
		cfg.OpenID = openid.Config{}
		cfg.Policy.OPA = opa.Args{
			URL:       &xnet.URL{},