code: func IsDownloadDeclinedError(err error) bool {
  	if e, ok := err.(interface {
  		DownloadDeclinedError() bool
  	}); ok {
  		return e.DownloadDeclinedError()
  	}
  	if parent := parentOf(err); parent != nil {
  		return IsDownloadDeclinedError(parent)
  	}
  	return false
  }
docs: // IsDownloadDeclinedError indicates that the smudge operation should not download.
  // TODO: I don't really like using errors to control that flow, it should be refactored.