const ABSENCE_PREFIXES: &[&str];Expand description
Deliberately few and specific. A prefix rejects every title that begins with it,
so “no title” and “title not” are NOT here: “No title bar on Windows” and “Title
not updating in swarm row” are real titles (ReAgent on #4185). Anything that is
only absence when it is the WHOLE reply belongs in ABSENCE_EXACT.