Merged PR with label conditions do not always result in the same action

[0xc0170]

An example can be found here: ARMmbed/mbed-os#12291

This is the rule:

  # Check if version label is applied
  - name: release version is a must for merged PRs
    conditions:
      - merged
      - -label~=^(release-version)
    actions:
      label:
        add: ['Release review required']
      comment:
        message: This PR does not contain release version label after merging.

I checked this in simulator and also on Github. The rule looks fine to me. But somehow we get the comment and label add for PRs that do not satisfy this rule. Only some PRs are affected.
What I suspect, if the label "release-version: xxx" is added after PR is being merged, might play a role here. It should not however.

[jd]

Yes, this is a race condition. When Mergify evaluates the rule, the PR is merged and then label is not set.

If you want to solve this right now you need to make sure your label is set before merging the PR.

(On our side, this kind of behavior should be improved when we switch to a more batched approach in treating GitHub events.)

[0xc0170]

Thanks for the input. We will make sure the label is there before merging, already been testing this today - works fine.