3efebb7948
This change passes on non succesful status codes for pagespeed resources and other places where we act as a content handler to nginx. This has two benefits: - Instead of a blank page, the user agent receives a formatted and (hopefully customized and informative) response. - Header modules are able to operate on that response, which was requested in https://github.com/pagespeed/ngx_pagespeed/issues/612#issuecomment-58855816