var (
		roots      []module.Version
		pathIsRoot = map[string]bool{mainModule.Path: true}
	)
	if v, ok := old.rootSelected("go"); ok {
		roots = append(roots, module.Version{Path: "go", Version: v})
		pathIsRoot["go"] = true
	}
	if v, ok := old.rootSelected("toolchain"); ok {
		roots = append(roots, module.Version{Path: "toolchain", Version: v})
		pathIsRoot["toolchain"] = true
	}