Fix one bug about socket session closed handling
Fix one bug about socket session closed handling

kerryjiang/SuperSocket,ZixiangBoy/SuperSocket,fryderykhuang/SuperSocket,ZixiangBoy/SuperSocket,mdavid/SuperSocket,jmptrader/SuperSocket,mdavid/SuperSocket,ZixiangBoy/SuperSocket,jmptrader/SuperSocket,chucklu/SuperSocket,fryderykhuang/SuperSocket,jmptrader/SuperSocket,memleaks/SuperSocket,chucklu/SuperSocket,mdavid/SuperSocket,kerryjiang/SuperSocket,fryderykhuang/SuperSocket,chucklu/SuperSocket