remove unused variable
remove unused variable

chainer/chainer,ktnyt/chainer,ktnyt/chainer,niboshi/chainer,tkerola/chainer,chainer/chainer,hvy/chainer,wkentaro/chainer,wkentaro/chainer,jnishi/chainer,hvy/chainer,chainer/chainer,jnishi/chainer,hvy/chainer,chainer/chainer,jnishi/chainer,okuta/chainer,okuta/chainer,jnishi/chainer,keisuke-umezawa/chainer,niboshi/chainer,pfnet/chainer,ktnyt/chainer,niboshi/chainer,ktnyt/chainer,niboshi/chainer,keisuke-umezawa/chainer,hvy/chainer,okuta/chainer,keisuke-umezawa/chainer,wkentaro/chainer,okuta/chainer,wkentaro/chainer,keisuke-umezawa/chainer