Merge pull request #42535 from kargakis/require-deployment-requeue-for-rollback

Automatic merge from submit-queue (batch tested with PRs 31783, 41988, 42535, 42572, 41870)

controller: ensure deployment rollback is re-entrant

Make rollbacks re-entrant in the Deployment controller, otherwise
fast enqueues of a Deployment may end up in undesired behavior
- redundant rollbacks.

Fixes https://github.com/kubernetes/kubernetes/issues/36703

@kubernetes/sig-apps-bugs

pkg/controller/deployment/util/deployment_util.go

@@ -661,6 +661,7 @@ func FindOldReplicaSets(deployment *extensions.Deployment, rsList []*extensions.
 			if newRS != nil && rs.UID == newRS.UID {
 				continue
 			}
+			// TODO: If there are no pods for a deployment, we will never return old replica sets....!
 			allOldRSs[rs.ObjectMeta.Name] = rs
 			if rsLabelsSelector.Matches(podLabelsSelector) {
 				oldRSs[rs.ObjectMeta.Name] = rs