SF bug #471720: ThreadingMixIn/TCPServer forgets close

Solved with a helper method that calls finish_request() and then
close_request().  The code is by Max Neunhöffer.
diff --git a/Misc/ACKS b/Misc/ACKS
index e7400e9..b17219a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -296,6 +296,7 @@
 Travers Naran
 Fredrik Nehr
 Chad Netzer
+Max Neunhöffer
 George Neville-Neil
 Oscar Nierstrasz
 Hrvoje Niksic