Fix for multi-gpu
Fix for multi-gpu

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