code: func getObjectDatabase() (*gitobj.ObjectDatabase, error) {
  	dir, err := git.GitCommonDir()
  	if err != nil {
  		return nil, errors.Wrap(err, "cannot open root")
  	}
  	return gitobj.FromFilesystem(filepath.Join(dir, "objects"), cfg.TempDir())
  }
docs: // getObjectDatabase creates a *git.ObjectDatabase from the filesystem pointed
  // at the .git directory of the currently checked-out repository.