Because this is skipped, it means that for HTTP 1.1 responses, if there is a Content-Length set, it goes to the code below which will buffer to try and find out what the content length should be.  If there is a content length set, it shouldn't buffer.  It also means that large files that we do know the content length of will always be served as chunked, since buffering them will always exceed the limit of the buffer and hence fallback to chunked.