remove a undefined global variable
remove a undefined global variable

wkentaro/chainer,benob/chainer,anaruse/chainer,keisuke-umezawa/chainer,jnishi/chainer,wkentaro/chainer,niboshi/chainer,ktnyt/chainer,jnishi/chainer,cupy/cupy,rezoo/chainer,okuta/chainer,keisuke-umezawa/chainer,cupy/cupy,ktnyt/chainer,okuta/chainer,kashif/chainer,AlpacaDB/chainer,ysekky/chainer,hvy/chainer,jnishi/chainer,niboshi/chainer,cupy/cupy,keisuke-umezawa/chainer,tkerola/chainer,aonotas/chainer,hvy/chainer,niboshi/chainer,chainer/chainer,delta2323/chainer,chainer/chainer,benob/chainer,ktnyt/chainer,cupy/cupy,AlpacaDB/chainer,chainer/chainer,wkentaro/chainer,hvy/chainer,keisuke-umezawa/chainer,hvy/chainer,okuta/chainer,ktnyt/chainer,pfnet/chainer,chainer/chainer,niboshi/chainer,kiyukuta/chainer,jnishi/chainer,kikusu/chainer,cemoody/chainer,okuta/chainer,ronekko/chainer,kikusu/chainer,wkentaro/chainer