Private dns=none clusters incorrectly creating bastion DNS name tasks

[rifelpet]

/kind bug
/kind failing-test

https://testgrid.k8s.io/kops-misc#kops-aws-private

kops is trying to create a DNS record for the bastion hosts:

 I0208 03:29:19.850427   14272 loader.go:90] Known tasks:
...
I0208 03:29:19.850581   14272 loader.go:92]   DNSName/bastion.e2e-e2e-kops-aws-private.test-cncf-aws.k8s.io
I0208 03:29:19.850589   14272 loader.go:92]   DNSName/bastion.e2e-e2e-kops-aws-private.test-cncf-aws.k8s.io-AAAA 

which then fails because the DNSZone task hasn't been defined, because the cluster uses dns=none:

Error: error building tasks: unexpected error resolving task "DNSName/bastion.e2e-e2e-kops-aws-private.test-cncf-aws.k8s.io": unable to find task "DNSZone/", referenced from DNSName/bastion.e2e-e2e-kops-aws-private.test-cncf-aws.k8s.io:Zone

The cluster.yaml shows a bastion's public name field is set:

  topology:
    bastion:
      bastionPublicName: bastion.e2e-e2e-kops-aws-private.test-cncf-aws.k8s.io
    dns:
      type: None

which is what creates the bastion DNSName tasks:

kops/pkg/model/awsmodel/bastion.go

Lines 399 to 407 in b73a2dd

	publicName := ""
	if b.Cluster.Spec.Networking.Topology != nil && b.Cluster.Spec.Networking.Topology.Bastion != nil {
	publicName = b.Cluster.Spec.Networking.Topology.Bastion.PublicName
	}
	if publicName != "" {
	// Here we implement the bastion CNAME logic
	// By default bastions will create a CNAME that follows the `bastion-$clustername` formula
	t := &awstasks.DNSName{
	Name: fi.PtrTo(publicName),

what I dont understand is how that field is being set in the cluster spec, because new_cluster.go only sets it if we're publishing DNS records:

kops/upup/pkg/fi/cloudup/new_cluster.go

Lines 1364 to 1368 in b73a2dd

	if cluster.PublishesDNSRecords() {
	cluster.Spec.Networking.Topology.Bastion = &api.BastionSpec{
	PublicName: "bastion." + cluster.Name,
	}
	}

kops/pkg/apis/kops/cluster.go

Lines 893 to 898 in 446f3ac

	func (c *Cluster) PublishesDNSRecords() bool {
	if c.UsesNoneDNS() || dns.IsGossipClusterName(c.Name) {
	return false
	}
	return true
	}

If we can have kops stop populating that cluster spec field for dns=none clusters, the DNSName tasks should stop being added.