add shutdown call to try to make redirect test more reliable

Author: Geoff Kizer

src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs

@@ -618,7 +618,6 @@ await LoopbackServer.CreateServerAsync(async (origServer, origUrl) =>
 
                         if (useTE)
                         {
-                            request.Content.Headers.ContentLength = 0;
                             request.Headers.TransferEncodingChunked = true;
                         }
                     }
@@ -633,6 +632,7 @@ await LoopbackServer.CreateServerAsync(async (redirServer, redirUrl) =>
                             // Send Connection: close so the client will close connection after request is sent,
                             // meaning we can just read to the end to get the content
                             await connection.ReadRequestHeaderAndSendResponseAsync((HttpStatusCode)statusCode, $"Location: {redirUrl}\r\nConnection: close\r\n");
+                            connection.Socket.Shutdown(SocketShutdown.Send);
                             await connection.Reader.ReadToEndAsync();
                         });
 
@@ -648,6 +648,7 @@ await LoopbackServer.CreateServerAsync(async (redirServer, redirUrl) =>
                             // Send Connection: close so the client will close connection after request is sent,
                             // meaning we can just read to the end to get the content
                             receivedRequest = await connection.ReadRequestHeaderAndSendResponseAsync(additionalHeaders: "Connection: close\r\n");
+                            connection.Socket.Shutdown(SocketShutdown.Send);
                             receivedContent = await connection.Reader.ReadToEndAsync();
                         });