Small fix to ensure tuple.
Small fix to ensure tuple.

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