code: func (c *DirConstraint) hasMatchingParent(ctx context.Context, s *search, parents map[blob.Ref]struct{}) (bool, error) {
  	for parent := range parents {
  		meta, err := s.blobMeta(ctx, parent)
  		if err != nil {
  			if os.IsNotExist(err) {
  				continue
  			}
  			return false, err
  		}
  		ok, err := c.blobMatches(ctx, s, parent, meta)
  		if err != nil {
  			return false, err
  		}
  		if ok {
  			return true, nil
  		}
  	}
  	return false, nil
  }
docs: // hasMatchingParent checks all parents against c and returns true as soon as one of
  // them matches, or returns false if none of them is a match.