- The ImageStream object should contain a new flag indicating that it refers to a manifest list
- openshift-controller-manager uses new openshift/api code to import image streams
- changing `importMode` of an image stream tag triggers a new import (i.e. updates generation in the tag spec)
- On pruner: sub-manifests may be GCed, in this case re-importing would solve the issue (until we work on the pruner).
- Relevant openshift-controller-manager code: https://github.com/openshift/openshift-controller-manager/blob/master/pkg/image/controller/imagestream_controller.go#L284-L289