Remove redundant copy
Remove redundant copy

niboshi/chainer,chainer/chainer,okuta/chainer,wkentaro/chainer,okuta/chainer,niboshi/chainer,wkentaro/chainer,wkentaro/chainer,chainer/chainer,wkentaro/chainer,niboshi/chainer,hvy/chainer,chainer/chainer,okuta/chainer,hvy/chainer,pfnet/chainer,chainer/chainer,hvy/chainer,okuta/chainer,hvy/chainer,niboshi/chainer