[HOLD] Spike: can we identify all changed files in a PR?

[pepopowitz]

DO NOT MERGE! I'm messing around.

Part of #1659.

Findings

1. ✅ The first two commits indicate that for the pull_request trigger, we can see all the files changed in this PR.
2. ❌ The third commit indicates that for the push trigger, we only see the files changed in the most recent commit.

• I might not be using the fetch-depth property of https://github.com/actions/checkout correctly. We might be able to fix number 2 above by passing the correct value of that field. I'm not finding very clear docs on what values for that field will accomplish what I'm looking for.
• I don't really know why we need to run build-docs on push. The workflow was configured that way before we added the pull_request trigger, but it's possible that we can remove the push trigger now that we're also running on pull_request.
  • I have a vague recollection of someone once telling me that some people like to see the results of build_docs before they open a PR. That's the only scenario I can think of where we would still need to run on push.
  • I've scheduled a post to #ask-documentation for Monday to find out if there are people who like to do that. I kind of suspect they don't exist, because the build takes so dang long these days and I can't imagine they'd wait for green before opening the PR.
  • This could also be a case of moving cheese for a few people for the sake of bettering the overall experience. If removing the push trigger enables us to speed up build times for everyone, that's a pretty significant net gain that might exceed the needs and wants of a couple people.

3. ✅ This PR demonstrates that the pull_request trigger, on forked PRs, would also give the full list of files changed in the PR.

[pepopowitz]

Closing this as it was for research purposes.