prevent calling "connClose" twice.

TimeManager is leaking because of "BlockedOnMVar".
Both TimeManger and Reaper do not use MVar at all.
TLS "bye" is the only registered function which uses MVar.
When TimeManager kills Warp, "bye" is called twice.
One is via "bracket", the other is by TimeManager.
This ensures that "bye" is called only once.
probably because TLS "bye" is called twice.

warp/Network/Wai/Handler/Warp/Run.hs

@@ -369,7 +369,7 @@ fork set mkConn addr app counter ii = settingsFork set $ \unmask -> do
                 -- above ensures the connection is closed.
                 when goingon $ serveConnection conn ii th addr transport set app
       where
-        register = T.registerKillThread (timeoutManager ii) (connClose conn)
+        register = T.registerKillThread (timeoutManager ii) (return ())
         cancel = T.cancel
 
     onOpen adr = increase counter >> settingsOnOpen set adr