auto issues the worker probe first and falls back to the plain path only when the origin returns
no x-cfw-* header at all -- a drupflare worker sets them on every /serve response including its
refusals, so their absence is the discriminator and the status code is not.
Probes one site and reports what answered.
autoissues the worker probe first and falls back to the plain path only when the origin returns nox-cfw-*header at all -- a drupflare worker sets them on every/serveresponse including its refusals, so their absence is the discriminator and the status code is not.