Don't set TE header for non-body responses

Resolves #952

Author: benaadams

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/Frame.cs

@@ -729,36 +729,37 @@ private void CreateResponseHeader(
 
             if (_keepAlive && !responseHeaders.HasTransferEncoding && !responseHeaders.HasContentLength)
             {
-                if (appCompleted)
+                // Don't set the Content-Length or Transfer-Encoding headers
+                // automatically for HEAD requests or 101, 204, 205, 304 responses.
+                if (Method != "HEAD" && StatusCanHaveBody(StatusCode))
                 {
-                    // Don't set the Content-Length or Transfer-Encoding headers
-                    // automatically for HEAD requests or 101, 204, 205, 304 responses.
-                    if (Method != "HEAD" && StatusCanHaveBody(StatusCode))
+                    if (appCompleted)
                     {
                         // Since the app has completed and we are only now generating
                         // the headers we can safely set the Content-Length to 0.
                         responseHeaders.SetRawContentLength("0", _bytesContentLengthZero);
                     }
-                }
-                else
-                {
-                    // Note for future reference: never change this to set _autoChunk to true on HTTP/1.0
-                    // connections, even if we were to infer the client supports it because an HTTP/1.0 request
-                    // was received that used chunked encoding. Sending a chunked response to an HTTP/1.0
-                    // client would break compliance with RFC 7230 (section 3.3.1):
-                    //
-                    // A server MUST NOT send a response containing Transfer-Encoding unless the corresponding
-                    // request indicates HTTP/1.1 (or later).
-                    if (_httpVersion == HttpVersionType.Http11)
-                    {
-                        _autoChunk = true;
-                        responseHeaders.SetRawTransferEncoding("chunked", _bytesTransferEncodingChunked);
-                    }
                     else
                     {
-                        _keepAlive = false;
+                        // Note for future reference: never change this to set _autoChunk to true on HTTP/1.0
+                        // connections, even if we were to infer the client supports it because an HTTP/1.0 request
+                        // was received that used chunked encoding. Sending a chunked response to an HTTP/1.0
+                        // client would break compliance with RFC 7230 (section 3.3.1):
+                        //
+                        // A server MUST NOT send a response containing Transfer-Encoding unless the corresponding
+                        // request indicates HTTP/1.1 (or later).
+                        if (_httpVersion == HttpVersionType.Http11)
+                        {
+                            _autoChunk = true;
+                            responseHeaders.SetRawTransferEncoding("chunked", _bytesTransferEncodingChunked);
+                        }
                     }
                 }
+
+                if (!appCompleted && _httpVersion != HttpVersionType.Http11)
+                {
+                    _keepAlive = false;
+                }
             }
 
             if (!_keepAlive && !hasConnection && _httpVersion != HttpVersionType.Http10)