I've just been failing to diagnose someone on IRC's problem with httpd returning 503 (Service Unavailable).
A look at the source turns up just one usage outside the script and proxy paths: in ap_http_filter, it returns SERVICE_UNAVAILABLE on encountering a chunked encoding error. This looks like a bug to me: surely that should return 400 on bad request from the client. The other case would be reading broken chunking coming from a backend when 502 (not 503) looks correct. But that's only really useful for logging, as it's unlikely to be encountered before the response status has been sent down the wire. Any strong rationale for 503, or should I just change it to 400? -- Nick Kew
