Prompted by hyperhive/hyperhive#3050: a reviewer held a formal
approve/request-changes verdict for CI to go green, which delayed a
merge that was only waiting on the review. CI, review approval, and
auto-merge arming are three independent gate conditions — a reviewer
is only responsible for the second one.
Documents the asymmetry that follows from auto-merge sometimes being
armed before a review lands: an unnecessary request-changes costs a
round-trip, but an approve given on lingering doubt can ship
immediately with no further human check. Default to holding when
unsure.
