Handle JOSH subtrees when milestoning rust-lang/rust PRs

[Urgau]

rustfmt is now a JOSH subtrees, let's modify the logic to check the modified files instead of checking if the same commit exists in the subtree repository.

This implements #2499 (comment):

So what I think we can do for Josh subtrees, if we ever get one that wants milestones, is to look at which files the commit modifies.

If the commit only modifies files inside the subtree and is named Merge pull request #{pr_number}, then we milestone the corresponding PR.

For the record:

• https://api.github.com/repos/rust-lang/rust/commits/31286787229bfc73cf10560b5ad74e43ad7c0952

cc @ytmimi @jieyouxu

[ytmimi]

@Urgau thank you for working on this!

For the record:

• https://api.github.com/repos/rust-lang/rust/commits/31286787229bfc73cf10560b5ad74e43ad7c0952

Nice, so that's referencing rust-lang/rust@3128678 from rust-lang/rust#163545

[Kobzol]

Thanks! If we alerady have the set of all files downloaded somewhere (I haven't checked), maybe we could do a pre-filter, and if none of them match the prefix, don't go fetch the changed files of the merge commits?

View changes since this review

[Urgau]

If we alerady have the set of all files downloaded somewhere (I haven't checked), maybe we could do a pre-filter, and if none of them match the prefix, don't go fetch the changed files of the merge commits?

That's already the case here:

triagebot/src/handlers/milestone_prs.rs

Lines 213 to 219 in d21a5ed

	for (repo, subtree) in [("rust-lang/rustfmt", "src/tools/rustfmt")] {
	if event_diff
	.files
	.iter()
	.any(|fd| fd.filename.starts_with(subtree))
	{
	// This PR touches the subtree so we'll try to assign milestones

[Kobzol]

Thanks!

View changes since this review

[ytmimi]

Thank you @Urgau for updating the milestone implementation for rustfmt and thank you @Kobzol for the review 🙏🏼