"Rejected by PR status" despite the check is validated

[curquiza]

Hello bors team!

Thanks for this awesome tool!

We have an issue with bors refusing to merge our PRs despite all the PR checks are validated.

We have a CI running to check a label has been put to the PR.
This check is put in the bors.toml as pr-status, see our settings

status = [
    'Tests on ubuntu-18.04 with stable',
    'Tests on macos-latest with stable',
    'Tests on windows-latest with stable',
    'Run Rustfmt',
]
pr_status = ['Specify breaking']
# 3 hours timeout
timeout-sec = 10800

We suceeded to merge other PRs, but we don't know why, for this one, bors refuses to merge despite the check is green ✅
The error is "Rejected by PR status"
In the dashboard, we don't have any history since Bors did not even launch.

Thanks in advance for your help 🙏

EDIT: some additional links: https://forum.bors.tech/t/rejected-by-pr-status-despite-the-check-is-validated/645

[curquiza]

Same issue here: meilisearch/milli#499

FYI, our Specify breaking check is not Required by GitHub

And we don't have this problem for every PR. It's random

EDIT: Now, no check are Required, and despite this, we still have the issue on multiple PRs

[curquiza]

We succeeded to merge both PRs by rebasing them, and then, trying to merge again. But avoiding rebasing is exactly the purpose of Bors, so not really a solution, but it worked 😇

EDIT: I had the issue again here, despite the branch was up-to-date: meilisearch/milli#501 and meilisearch/milli#503

[MarkVaughn]

We have a similar issue, this looks to be because of the trigger of the status being not tied to the latest commit/push but to the pull_request

on:
  pull_request:
    types: [labeled, unlabeled, opened, edited, synchronize]

https://github.com/meilisearch/milli/blob/main/.github/workflows/enforce-label.yml

What I'm guessing is happening is you open a PR without the label and the status fails on the commit. Then you add the label and the check runs again and passes on the PR, but bors still sees the failure on the last commit.

In our case it is a PR title check. Was hoping that this is a known bug that might be addressed. Might be a bit fringe

[kaspar030]

Seems like we're having the same issue here: RIOT-OS/RIOT#19029