docs: def get_signatures_with_results(vcs):
      """Returns the list of signatures for which test results are saved.
  
      Args:
          vcs (easyci.vcs.base.Vcs)
  
      Returns:
          List[str]
      """
      results_dir = os.path.join(vcs.private_dir(), 'results')
      if not os.path.exists(results_dir):
          return []
      rel_paths = os.listdir(results_dir)
      return [p for p in rel_paths if os.path.isdir(os.path.join(results_dir, p))]