code: func HasRevisionHistoryLimit(d *apps.Deployment) bool {
  	return d.Spec.RevisionHistoryLimit != nil && *d.Spec.RevisionHistoryLimit != math.MaxInt32
  }
docs: // HasRevisionHistoryLimit checks if the Deployment d is expected to keep a specified number of
  // old replicaSets. These replicaSets are mainly kept with the purpose of rollback.
  // The RevisionHistoryLimit can start from 0 (no retained replicasSet). When set to math.MaxInt32,
  // the Deployment will keep all revisions.