code: func EnvRootFromStampPath(path string) (string, error) {
  	if err := filesystem.AbsPath(&path); err != nil {
  		return "", errors.Annotate(err,
  			"failed to get absolute path for specification file path: %s", path).Err()
  	}
  	return filepath.Dir(filepath.Dir(path)), nil
  }
docs: // EnvRootFromStampPath calculates the environment root from an exported
  // environment specification file path.
  //
  // The specification path is: <EnvRoot>/<SpecHash>/EnvironmentStampPath, so our
  // EnvRoot is two directories up.
  //
  // We export EnvSpecPath as an asbolute path. However, since someone else
  // could have overridden it or exported their own, let's make sure.