code: func oldPasswordUpgrade(pass string) (string, error) {
  	hash1, err := hex.DecodeString(pass)
  	if err != nil {
  		return "", errors.Trace(err)
  	}
  
  	hash2 := auth.Sha1Hash(hash1)
  	newpass := fmt.Sprintf("*%X", hash2)
  	return newpass, nil
  }
docs: // oldPasswordUpgrade upgrade password to MySQL compatible format