podman: Intermediate layers for tagged images are incorrectly pruned

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

podman-image-prune incorrectly prunes intermediate layers for tagged images.

Steps to reproduce the issue:

Consider the following Dockerfile:

FROM scratch
ENV test1=test1
ENV test2=test2

then,

$ podman build . -t test
STEP 1: FROM scratch
STEP 2: ENV test1=test1
--> f106d67818d
STEP 3: ENV test2=test2
STEP 4: COMMIT test
--> 3775b6bda38
Successfully tagged localhost/test:latest
3775b6bda38dc3cf77b00e540706c367bc7d6fff606bbc7eab75842fcb2f41a8
$ podman image prune 
WARNING! This will remove all dangling images.
Are you sure you want to continue? [y/N] y
f106d67818dd8ee583d3fb3052a87705ac8c953c9c9e3ce453b51a9da57e1271

Describe the results you received:

As you can see, intermediate layer f106d67818d was removed.

Describe the results you expected:

It shouldn’t be removed. FWIW, docker doesn’t remove it.

Output of podman version:

Version:      3.2.1
API Version:  3.2.1
Go Version:   go1.16.3
Built:        Mon Jun 14 21:12:29 2021
OS/Arch:      linux/amd64

Output of podman info --debug:

host:
  arch: amd64
  buildahVersion: 1.21.0
  cgroupControllers: []
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: conmon-2.0.27-2.fc34.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.0.27, commit: '
  cpus: 8
  distribution:
    distribution: fedora
    version: "34"
  eventLogger: journald
  hostname: ****
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 5.12.11-300.fc34.x86_64
  linkmode: dynamic
  memFree: 6931976192
  memTotal: 16467206144
  ociRuntime:
    name: crun
    package: crun-0.20.1-1.fc34.x86_64
    path: /usr/bin/crun
    version: |-
      crun version 0.20.1
      commit: 0d42f1109fd73548f44b01b3e84d04a279e99d2e
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  remoteSocket:
    path: /run/user/1000/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: true
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.1.9-1.fc34.x86_64
    version: |-
      slirp4netns version 1.1.8+dev
      commit: 6dc0186e020232ae1a6fcc1f7afbc3ea02fd3876
      libslirp: 4.4.0
      SLIRP_CONFIG_VERSION_MAX: 3
      libseccomp: 2.5.0
  swapFree: 14918758400
  swapTotal: 16932397056
  uptime: 50h 1m 6.28s (Approximately 2.08 days)
registries:
  search:
  - registry.fedoraproject.org
  - registry.access.redhat.com
  - docker.io
  - quay.io
store:
  configFile: /home/****/.config/containers/storage.conf
  containerStore:
    number: 1
    paused: 0
    running: 0
    stopped: 1
  graphDriverName: overlay
  graphOptions:
    overlay.mount_program:
      Executable: /usr/bin/fuse-overlayfs
      Package: fuse-overlayfs-1.5.0-1.fc34.x86_64
      Version: |-
        fusermount3 version: 3.10.4
        fuse-overlayfs: version 1.5
        FUSE library version 3.10.4
        using FUSE kernel interface version 7.31
  graphRoot: /home/****/.local/share/containers/storage
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  imageStore:
    number: 12
  runRoot: /run/user/1000
  volumePath: /home/****/.local/share/containers/storage/volumes
version:
  APIVersion: 3.2.1
  Built: 1623697949
  BuiltTime: Mon Jun 14 21:12:29 2021
  GitCommit: ""
  GoVersion: go1.16.3
  OsArch: linux/amd64
  Version: 3.2.1

Package info (e.g. output of rpm -q podman or apt list podman):

podman-3.2.1-1.fc34.x86_64

Have you tested with the latest version of Podman and have you checked the Podman Troubleshooting Guide? (https://github.com/containers/podman/blob/master/troubleshooting.md)

No