Feature request: support manual r? without automatic reviewer assignment

[RalfJung]

In Miri we generally don't use automatic reviewer assignment, instead one of us just grabs a PR when something still needs review. It would still be nice to be able to use r? though. So it would be nice if triagebot could let us use r? without automatically assigning someone to every new PR.

[apiraino]

@RalfJung ok so basically disable automatic assignment when a new PR with A-miri label is created, correct? There are also a number of labels in the same area (A-mir*). Should they be ignored as well?

EDIT: Or are you talking about the rust-lang/miri repository, don't you? So the rule should be: don't autoassign PRs for that repo?

[RalfJung]

This is for PRs in https://github.com/rust-lang/miri/, so no there's no label involved. I am just looking for a way to say in triagebot.toml that we want to support r? but not have anyone automatically assigned.

EDIT: Or are you talking about the rust-lang/miri repository, don't you? So the rule should be: don't autoassign PRs for that repo?

Yes, that.