"fix client send empty gradients bug"
"fix client send empty gradients bug"

reyoung/Paddle,chengduoZH/Paddle,PaddlePaddle/Paddle,reyoung/Paddle,yu239/Paddle,lcy-seso/Paddle,baidu/Paddle,Canpio/Paddle,pengli09/Paddle,yu239/Paddle,lispc/Paddle,reyoung/Paddle,pkuyym/Paddle,reyoung/Paddle,lispc/Paddle,baidu/Paddle,pengli09/Paddle,tensor-tang/Paddle,hedaoyuan/Paddle,lcy-seso/Paddle,lispc/Paddle,lispc/Paddle,lispc/Paddle,chengduoZH/Paddle,lcy-seso/Paddle,yu239/Paddle,pengli09/Paddle,luotao1/Paddle,luotao1/Paddle,chengduoZH/Paddle,yu239/Paddle,reyoung/Paddle,pkuyym/Paddle,tensor-tang/Paddle,pengli09/Paddle,pengli09/Paddle,pkuyym/Paddle,chengduoZH/Paddle,lispc/Paddle,putcn/Paddle,tensor-tang/Paddle,Canpio/Paddle,QiJune/Paddle,reyoung/Paddle,yu239/Paddle,jacquesqiao/Paddle,hedaoyuan/Paddle,PaddlePaddle/Paddle,pengli09/Paddle,putcn/Paddle,PaddlePaddle/Paddle,hedaoyuan/Paddle,Canpio/Paddle,tensor-tang/Paddle,Canpio/Paddle,hedaoyuan/Paddle,pkuyym/Paddle,QiJune/Paddle,luotao1/Paddle,jacquesqiao/Paddle,pengli09/Paddle,QiJune/Paddle,pkuyym/Paddle,luotao1/Paddle,PaddlePaddle/Paddle,QiJune/Paddle,jacquesqiao/Paddle,Canpio/Paddle,baidu/Paddle,jacquesqiao/Paddle,hedaoyuan/Paddle,yu239/Paddle,lcy-seso/Paddle,yu239/Paddle,Canpio/Paddle,chengduoZH/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,QiJune/Paddle,jacquesqiao/Paddle,lcy-seso/Paddle,hedaoyuan/Paddle,luotao1/Paddle,PaddlePaddle/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,Canpio/Paddle,putcn/Paddle,baidu/Paddle,jacquesqiao/Paddle,baidu/Paddle,hedaoyuan/Paddle,QiJune/Paddle,lispc/Paddle,hedaoyuan/Paddle,pengli09/Paddle,putcn/Paddle,pkuyym/Paddle,Canpio/Paddle,tensor-tang/Paddle,putcn/Paddle,lcy-seso/Paddle,lispc/Paddle,putcn/Paddle,yu239/Paddle