Solid, thanks for extending the test infra too with this change!

extending the test infra

Actually, I did have a question about this: I just added a labels property to the PullRequest class, but I wasn't sure if that was the right thing to do since I couldn't find that in the GraphQL schema we use; is that OK?

Actually, I did have a question about this: I just added a labels property to the PullRequest class, but I wasn't sure if that was the right thing to do since I couldn't find that in the GraphQL schema we use; is that OK?

Oh it's probably in the Issue class (every PullRequest is an Issue). Do you see it now? Labels are modeled in a sort of complicated way but it would be good to do it properly.

@ezyang I updated this PR to fix the GraphQL test infra for labels (see also grantjenks/python-sortedcontainers#107 for more context on some of those changes), and changed it so now it applies the --labels to all PRs in the stack instead of just the new ones; asking for review again

@ezyang I fixed the mutable argument default and simplified the test_labels helper function

@samestep and I chatted about this PR and we agreed to park it for now while waiting for more details about optionally triggered CI builds to pan out. The label GraphQL changes are generally useful and we should make sure they eventually get merged, even if we don't actually have the --label argument.

Closing this for now since there aren't currently plans to merge it.