Function is_exempt 

fn is_exempt(relative: &str) -> bool

Is this repository-relative path inside the exempt directory?

A path, not a string prefix. relative.starts_with(EXEMPT) also matched docs/designs/, docs/design-notes.md and any future docs/designing-a-sampler.md — three plausible names for published pages, each of which would then have been exempt from every check with nothing saying so, because the printed exemption names docs/design/** (§1.3.152).