Populate FILES variable if PR contains one file in data/

[probonopd]

Populate FILES variable if PR contains one file in data/.

Currently often in PRs the FILES variable is empty when an existing PR gets updated by pressing the "Update branch" button or using Mergify, e.g., here for f578718:
#2541

Log:
https://github.com/AppImage/appimage.github.io/runs/3149918916

In those situations, I manually have to go into the file in data/ in the PR, make a trivial edit (e.g., add a line with a # in it) to trigger another test run where the changed file then is picked up in the FILES variable.

So we would somehow need to look at the PR and find out if file(s) in data/ have been affected by the PR, and populate the FILES variable with them.

@andy5995 do you have an idea how to do that?

Without having this, using Mergify (which automates pressing the "Update branch" button) is of no actual use to us.

[andy5995]

So we would somehow need to look at the PR and find out if file(s) in data/ have been affected by the PR, and populate the FILES variable with them.

@andy5995 do you have an idea how to do that?

Not a clue.

In my experience, using update branch which I think is the same as rebasing is often not necessary.

Though the migration from Travis to Actions will require most existing PRs to be rebased, normally I don't think rebasing should be necessary. Primarily rebasing the master branch onto a PR or feature branch is required when the changes are dependent on a change that's been committed to master.

Unfortunately that's not much help since right now, most of the existing PRs will need rebasing so they run the new test on Actions.

I don't know how much difference there is in using update branch or rebasing. So far it seems whenever I locally rebase #2553 that the FILES variable is ok.