code: func normalizeWorkdirUnix(current string, requested string) (string, error) {
  	if requested == "" {
  		return "", errors.New("cannot normalize nothing")
  	}
  	current = strings.Replace(current, string(os.PathSeparator), "/", -1)
  	requested = strings.Replace(requested, string(os.PathSeparator), "/", -1)
  	if !path.IsAbs(requested) {
  		return path.Join(`/`, current, requested), nil
  	}
  	return requested, nil
  }
docs: // normalizeWorkdirUnix normalizes a user requested working directory in a
  // platform semantically consistent way.