fix thrift registration to return the underlying handler
fix thrift registration to return the underlying handler

hustxiaoc/tchannel,RyanTech/tchannel,vanloswang/tchannel,RyanTech/tchannel,vanloswang/tchannel,hustxiaoc/tchannel,bunnyblue/tchannel,chenwenbin928/tchannel,savaki/tchannel,hustxiaoc/tchannel,bunnyblue/tchannel,benfleis/tchannel,Zirpon/tchannel,Zirpon/tchannel,Zirpon/tchannel,chenwenbin928/tchannel,i/tchannel,chenwenbin928/tchannel,benfleis/tchannel,i/tchannel,i/tchannel,sasa233/tchannel,vanloswang/tchannel,sasa233/tchannel,savaki/tchannel,bunnyblue/tchannel,savaki/tchannel,RyanTech/tchannel,sasa233/tchannel,benfleis/tchannel