fix

Author: honfika

src/Titanium.Web.Proxy/RequestHandler.cs

@@ -159,7 +159,18 @@ await HeaderParser.ReadHeaders(clientStream, args.HttpClient.Request.Headers,
                                 }
 
                                 prefetchTask = null;
+                            }
 
+                            if (connection != null)
+                            {
+                                var socket = connection.TcpSocket;
+                                bool part1 = socket.Poll(1000, SelectMode.SelectRead);
+                                bool part2 = socket.Available == 0;
+                                if (part1 & part2)
+                                {
+                                    //connection is closed
+                                    connection = null;
+                                }
                             }
 
                             // create a new connection if cache key changes.