return nil, err
	}
	versions.Origin = nil
	var list []string
	have := make(map[string]bool)
	goPrefix := ""
	if r.path == "toolchain" {
		goPrefix = "go"
	}
	for _, v := range versions.List {
		v, ok := dlToGo(v)
		if !ok {
			continue
		}
		if !have[v] {
			have[v] = true
			list = append(list, goPrefix+v)
		}
	}

	// Always include our own version.