Add command line option to specify labels about ghstack

[SplitInfinity]

I couldn't find anything about labels in the API docs for creating a PR, so I did some quick Googling and found octokit/octokit.net#1862, which seems to imply that, while you can use the API to add a label right after the PR is created, there isn't a way to add the label while creating it. I could be mistaken though, since that issue is a few years old and also on a .NET-specific repo.

Would this still fit your use case? It would require another network round-trip but that's probably fine; I guess the question is whether this label application would happen before or after pytorch-probot queries for labels.

My use case is applying labels to my PRs so that the right tests run on them in the pytorch/pytorch repo.

Also, should the labels given on the command line be applied to all PRs in the stack even if they already exist, or only newly created PRs?

I think a --all option might be useful here to distinguish between the two.

[samestep]

I couldn't find anything about labels in the API docs for creating a PR, so I did some quick Googling and found octokit/octokit.net#1862, which seems to imply that, while you can use the API to add a label right after the PR is created, there isn't a way to add the label while creating it. I could be mistaken though, since that issue is a few years old and also on a .NET-specific repo.

Would this still fit your use case? It would require another network round-trip but that's probably fine; I guess the question is whether this label application would happen before or after pytorch-probot queries for labels.

Also, should the labels given on the command line be applied to all PRs in the stack even if they already exist, or only newly created PRs?