Enable milestone munger for PRs

[marun]

As per a request from @enisoc to have PRs in the milestone maintained by the munger ahead of code slush/freeze. The majority of the changes are to ensure the correct object type (issue/pr) is referenced in notifications. In addition to minor test updates, I've manually tested the munger against a personal repository.

cc: @jberkus

[enisoc]

/assign @apelisse

Antoine, could you take a look? I'd like to enable this as soon as possible, so we'll be ready for code slush on Monday.

[apelisse]

yeah, looks good to me.
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: apelisse, marun

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[enisoc]

@cjwagner Are you the one who deploys munger updates?

[cjwagner]

Yeah I'll update the k/k deployment.

[xiangpengzhao]

@marun kubernetes/kubernetes#55812 has both status/approved-for-milestone (added manually) and milestone/incomplete-labels. Is this status expected?

[enisoc]

@xiangpengzhao That one needs a priority/* label: kubernetes/kubernetes#55812 (comment)

[xiangpengzhao]

@enisoc yeah I saw that comment. What I was thinking of is the milestone workflow (IIRC):

• PR is marked in the milestone, then [UPDATE: add this bullet]
• PR has milestone/incomplete-labels, then
• PR has all of priority/*, kind/*, sig/*, then
• PR removes milestone/incomplete-labels and adds milestone/complete-labels, then
• PR is approved for milestone, it gets status/approved-for-milestone.

So I wonder if it's a correct status that a PR has both status/approved-for-milestone and milestone/incomplete-labels like the linked PR does. If not, the bot should remove the manually added status/approved-for-milestone until all the expected labels are labeled.

[enisoc]

I don't think we should remove status/approved-for-milestone in this case. That's often added by someone who's in milestone-maintainers doing a drive-by to approve an issue. We shouldn't require that person to also set the other labels before approving, and we shouldn't make them have to come back again because status/approved-for-milestone didn't stick.

[xiangpengzhao]

@enisoc agreed :)

[xiangpengzhao]

another thing, after the final label status/approved-for-milestone is added, do we still need the last comment? See: kubernetes/kubernetes#55803 (comment)