A buffered request whose response body went over set_payload_max_length(),
also once decompressed, failed with Error::Read, while the Stream API
reports the same limit as Error::ExceedMaxPayloadSize. read_content()
already marks it with a 413 status, so map that status to
ExceedMaxPayloadSize next to the 415 and 500 the client maps already.
d99c697be6
