Packer docker builder does not reset ENTRYPOINT properly

This issue was originally opened by @bertramn as hashicorp/packer#7487. It was migrated here as a result of the Packer plugin split. The original body of the issue is below.

We are using packer to build a container with a parent that includes an entrypoint. In the packer build we "reset" entrypoint with ENTRYPOINT []. Unfortunately the container is being committed with the entrypoint of the parent still in place.

Doing this in a Dockerfile gets rid of the entrypoint from parent:

FROM ep-issue:parent
ENTRYPOINT []
CMD []

While the same in packer version does not:

{
  "builders": [
    {
      "type": "docker",
      "image": "ep-issue:parent",
      "pull": "false",
      "commit": "true",
      "changes": [
        "ENTRYPOINT []",
        "CMD []"
      ]
    }
  ],
  "post-processors": [
    {
      "type": "docker-tag",
      "repository": "ep-issue",
      "tag": "child2"
    }
  ]
}

Packer version v1.3.5
Host platform MacOS High Sierra
Gist of packer-entrypoint-build.log
Gist of the simple script to reproduce the bug

hashicorp / packer-plugin-docker

Packer docker builder does not reset ENTRYPOINT properly #13