fix: don't allow publishing within a draft change log context

[bradenmacdonald]

I'm not sure if this is best described as a fix: or a feat!:, but I'm opening this PR so we can consider re-landing this additional validation.

This PR disallows any publish APIs within a bulk draft changes context.

For the record, before we merge it, we have to refactor openedx-platform's modulestore_migrator: openedx/openedx-platform#38508

Part of #463 . Originally merged as part of #521 but later reverted in #574 after we discovered the modulestore_migrator issue.

Motivation

Allowing publishes within a draft change context risks publishing snapshots that are in an intermediate draft state. A DraftChangeLog is designed to collapse repeated edits to the same entity into a single record (old→final) at exit — see _add_to_existing_draft_change_log. If you do set_draft_version(A, v2); publish_all_drafts(...); set_draft_version(A, v3) inside the same context, Published.version ends up at v2 (a transient mid-bulk state), while the DraftChangeLog records A: v1 → v3. The publish captures a state that was never a settled state of the bulk change. (particularly relevant with events that get emitted, as published events would be emitted before draft events.)

Furthermore, in the specific case of modulestore_migrator it currently does something we definitely don't want: it groups all the migrated drafts into a single draft change log, but it creates many separate publish logs - one for each imported component and container.

Alternative

An alternative validation could be to allow publishes within a bulk draft changes context, but then disallow any further draft changes to those entities which are published. I don't really like this approach though as it requires a lot more bookkeeping. It would allow us to keep the modulestore_migrator code unchanged, but I think that's not good because it still has this problematic creation of many publish logs.

[openedx-webhooks]

Thanks for the pull request, @bradenmacdonald!

This repository is currently maintained by @axim-engineering.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

• If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
  • This process (including the steps you'll need to take) is documented here.
• If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

• Dependencies

  This PR must be merged before / after / at the same time as ...

• Blockers

  This PR is waiting for OEP-1234 to be accepted.

• Timeline information

  This PR must be merged by XX date because ...

• Partner information

  This is for a course on edx.org.

• Supporting documentation
• Relevant Open edX discussion forum threads

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

Details

---

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

• Overview of Review Process for Community Contributions
• Pull Request Status Guide
• Making changes to your pull request

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

• The size and impact of the changes that it introduces
• The need for product review
• Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.