Mirroring a manifest-list-based release payload with --to-image-stream uses Legacy importMode and does not honor --keep-manifest-list

When mirroring a multiarch release payload through oc adm release mirror --keep-manifest-list --to-image-stream into an image stream of a cluster's internal registry, the cluster does not import the image as a manifest list.

4.15

Always

1. oc adm release mirror \
                  --from=quay.io/openshift-release-dev/ocp-release:4.14.0-rc.5-multi \
                  --to-image-stream=release \
                  --keep-manifest-list=true
2. oc get istag release:installer -o yaml
3.

apiVersion: image.openshift.io/v1
generation: 1
image:
  dockerImageLayers:
  - mediaType: application/vnd.docker.image.rootfs.diff.tar.gzip
    name: sha256:97da74cc6d8fa5d1634eb1760fd1da5c6048619c264c23e62d75f3bf6b8ef5c4
    size: 79524639
  - mediaType: application/vnd.docker.image.rootfs.diff.tar.gzip
    name: sha256:d8190195889efb5333eeec18af9b6c82313edd4db62989bd3a357caca4f13f0e
    size: 1438
  - mediaType: application/vnd.docker.image.rootfs.diff.tar.gzip
    name: sha256:09c3f3b6718f2df2ee9cd3a6c2e19ddb73ca777f216d310eaf4e0420407ea7c7
    size: 59044444
  - mediaType: application/vnd.docker.image.rootfs.diff.tar.gzip
    name: sha256:cf84754d71b4b704c30abd45668882903e3eaa1355857b605e1dbb25ecf516d7
    size: 11455659
  - mediaType: application/vnd.docker.image.rootfs.diff.tar.gzip
    name: sha256:2e20a50f4b685b3976028637f296ae8839c18a9505b5f58d6e4a0f03984ef1e8
    size: 433281528
  dockerImageManifestMediaType: application/vnd.docker.distribution.manifest.v2+json
  dockerImageMetadata:
    Architecture: amd64
    Config:
      Entrypoint:
      - /bin/openshift-install
      Env:
      - container=oci
      - GODEBUG=x509ignoreCN=0,madvdontneed=1
      - __doozer=merge
      - BUILD_RELEASE=202310100645.p0.gc926532.assembly.stream
      - BUILD_VERSION=v4.15.0
      - OS_GIT_MAJOR=4
      - OS_GIT_MINOR=15
      - OS_GIT_PATCH=0
      - OS_GIT_TREE_STATE=clean
      - OS_GIT_VERSION=4.15.0-202310100645.p0.gc926532.assembly.stream-c926532
      - SOURCE_GIT_TREE_STATE=clean
      - __doozer_group=openshift-4.15
      - __doozer_key=ose-installer
      - OS_GIT_COMMIT=c926532
      - SOURCE_DATE_EPOCH=1696907019
      - SOURCE_GIT_COMMIT=c926532cd50b6ef4974f14dfe3d877a0f7707972
      - SOURCE_GIT_TAG=agent-installer-v4.11.0-dev-preview-2-2165-gc926532cd5
      - SOURCE_GIT_URL=https://github.com/openshift/installer
      - PATH=/bin
      - HOME=/output
      Labels:
        License: GPLv2+
        architecture: x86_64
        build-date: 2023-10-10T10:01:18
        com.redhat.build-host: cpt-1001.osbs.prod.upshift.rdu2.redhat.com
        com.redhat.component: ose-installer-container
        com.redhat.license_terms: https://www.redhat.com/agreements
        description: This is the base image from which all OpenShift Container Platform
          images inherit.
        distribution-scope: public
        io.buildah.version: 1.29.0
        io.k8s.description: This is the base image from which all OpenShift Container
          Platform images inherit.
        io.k8s.display-name: OpenShift Container Platform RHEL 8 Base
        io.openshift.build.commit.id: c926532cd50b6ef4974f14dfe3d877a0f7707972
        io.openshift.build.commit.url: https://github.com/openshift/installer/commit/c926532cd50b6ef4974f14dfe3d877a0f7707972
        io.openshift.build.source-location: https://github.com/openshift/installer
        io.openshift.expose-services: ""
        io.openshift.maintainer.component: Installer / openshift-installer
        io.openshift.maintainer.project: OCPBUGS
        io.openshift.release.operator: "true"
        io.openshift.tags: openshift,base
        maintainer: Red Hat, Inc.
        name: openshift/ose-installer
        release: 202310100645.p0.gc926532.assembly.stream
        summary: Provides the latest release of the Red Hat Extended Life Base Image.
        url: https://access.redhat.com/containers/#/registry.access.redhat.com/openshift/ose-installer/images/v4.15.0-202310100645.p0.gc926532.assembly.stream
        vcs-ref: d40a2800e169f6c2d63897467af22d59933e8811
        vcs-type: git
        vendor: Red Hat, Inc.
        version: v4.15.0
      User: 1000:1000
      WorkingDir: /output
    ContainerConfig: {}
    Created: "2023-10-10T10:59:36Z"
    Id: sha256:ae4c47d3c08de5d57b5d4fa8a30497ac097c05abab4e284c91eae389e512f202
    Size: 583326767
    apiVersion: image.openshift.io/1.0
    kind: DockerImage
  dockerImageMetadataVersion: "1.0"
  dockerImageReference: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:67d35b2185c9f267523f86e54f403d0d2561c9098b7bb81fa3bfd6fd8a121d04
  metadata:
    annotations:
      image.openshift.io/dockerLayersOrder: ascending
    creationTimestamp: "2023-10-11T10:56:53Z"
    name: sha256:67d35b2185c9f267523f86e54f403d0d2561c9098b7bb81fa3bfd6fd8a121d04
    resourceVersion: "740341"
    uid: 17dede63-ca3b-47ad-a157-c78f38c1df7d
kind: ImageStreamTag
lookupPolicy:
  local: true
metadata:
  creationTimestamp: "2023-10-12T09:32:10Z"
  name: release:installer
  namespace: okd-fcos
  resourceVersion: "1329147"
  uid: d6cfcd4d-3f9c-4bb1-bc56-04bf5e926628
tag:
  annotations: null
  from:
    kind: DockerImage
    name: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:c510f0e2bd29f7b9bf45146fbc212e893634179cc029cd54a135f05f9ae1df52
  generation: 12
  importPolicy:
    importMode: Legacy
  name: installer
  referencePolicy:
    type: Source

apiVersion: image.openshift.io/v1
generation: 12
image:
  dockerImageManifestMediaType: application/vnd.docker.distribution.manifest.list.v2+json
  dockerImageManifests:
  - architecture: amd64
    digest: sha256:67d35b2185c9f267523f86e54f403d0d2561c9098b7bb81fa3bfd6fd8a121d04
    manifestSize: 1087
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: arm64
    digest: sha256:a602c3e4b5f8f747b2813ed2166f366417f638fc6884deecebdb04e18431fcd6
    manifestSize: 1087
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: ppc64le
    digest: sha256:04296057a8f037f20d4b1ca20bcaac5bdca5368cdd711a3f37bd05d66c9fdaec
    manifestSize: 1087
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: s390x
    digest: sha256:5fda4ea09bfd2026b7d6acd80441b2b7c51b1cf440fd46e0535a7320b67894fb
    manifestSize: 1087
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  dockerImageMetadata:
    ContainerConfig: {}
    Created: "2023-10-12T09:32:03Z"
    Id: sha256:c510f0e2bd29f7b9bf45146fbc212e893634179cc029cd54a135f05f9ae1df52
    apiVersion: image.openshift.io/1.0
    kind: DockerImage
  dockerImageMetadataVersion: "1.0"
  dockerImageReference: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:c510f0e2bd29f7b9bf45146fbc212e893634179cc029cd54a135f05f9ae1df52
  metadata:
    creationTimestamp: "2023-10-12T09:32:10Z"
    name: sha256:c510f0e2bd29f7b9bf45146fbc212e893634179cc029cd54a135f05f9ae1df52
    resourceVersion: "1327949"
    uid: 4d78c9ba-12b2-414f-a173-b926ae019ab0
kind: ImageStreamTag
lookupPolicy:
  local: true
metadata:
  creationTimestamp: "2023-10-12T09:32:10Z"
  name: release:installer
  namespace: okd-fcos
  resourceVersion: "1329147"
  uid: d6cfcd4d-3f9c-4bb1-bc56-04bf5e926628
tag:
  annotations: null
  from:
    kind: DockerImage
    name: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:c510f0e2bd29f7b9bf45146fbc212e893634179cc029cd54a135f05f9ae1df52
  generation: 12
  importPolicy:
    importMode: PreserveOriginal
  name: installer
  referencePolicy:
    type: Source