finalPkgpath, underGoRoot, err := subdir()
	if err != nil {
		return "", err
	}
	cwd = strings.TrimSuffix(cwd, finalPkgpath)

	// Copy all immediate files and testdata directories between
	// the package being tested and the source root.
	pkgpath = ""
	for _, element := range strings.Split(finalPkgpath, string(filepath.Separator)) {
		if debug {
			log.Printf("copying %s", pkgpath)
		}
		pkgpath = filepath.Join(pkgpath, element)