Update how we detect overlapping deployments

When looking for overlapping deployments, we should also find other deployments that select current deployment's pods,
not just the ones whose pods are selected by current deployment.

pkg/controller/deployment/deployment_controller.go

@@ -382,17 +382,17 @@ func (dc *DeploymentController) syncDeployment(key string) error {
 // the newer overlapping ones (only sync the oldest one). New/old is determined by when the
 // deployment's selector is last updated.
 func (dc *DeploymentController) handleOverlap(d *extensions.Deployment) error {
-	selector, err := unversioned.LabelSelectorAsSelector(d.Spec.Selector)
-	if err != nil {
-		return fmt.Errorf("deployment %s/%s has invalid label selector: %v", d.Namespace, d.Name, err)
-	}
 	deployments, err := dc.dLister.Deployments(d.Namespace).List(labels.Everything())
 	if err != nil {
 		return fmt.Errorf("error listing deployments in namespace %s: %v", d.Namespace, err)
 	}
 	overlapping := false
 	for _, other := range deployments {
-		if !selector.Empty() && selector.Matches(labels.Set(other.Spec.Template.Labels)) && d.UID != other.UID {
+		foundOverlaps, err := util.OverlapsWith(d, other)
+		if err != nil {
+			return err
+		}
+		if foundOverlaps {
 			deploymentCopy, err := util.DeploymentDeepCopy(other)
 			if err != nil {
 				return err