Discovered a bug with KeepAlives

[nmosafi]

I am hosting in IIS using owin.host.systemweb
I have a single client repeatedly GETing and POSTing some resources
I get the error "The server committed a protocol violation. Section=ResponseStatusLine" eventually

Here is a small test app to demonstrate it. A WebApp which just hosts a single resource, and a Console app which continually GETs and POSTs to the the WebApp. After running this, an error is shown very quickly

[nmosafi]

Note I wouldn't expect this to be merged, it's just to demonstrate an issue

[serialseb]

Copied over from slack:

thinking out loud but could it be that somehow the returned result is incorrectly returned and eventually the server throws because of that?
i noticed that the newtonsoft codec always writes without bom but reads with the BOM-eanbled UTF8
but you write the request with a BOM and no content-length
so a few silly ideas here to see if it has any effect:

1. is the request stream flushed when it’s disposed?
2. Is writing with a new UTF8Encoding(false) instead chaanging the behaviour?
3. Is using the UTF8Encoding(false) in the NewtonsoftJsonCodec reader changing any of the behaviour?
4. Is adding a content-length in the request solving the problem?
5. is the request or the response going out as chunked or is that configured to always buffer in systemweb? I got litterally 0 experience on runnign that
   and finally, is doing the same test with HttpClient resulting in any different behaviour?