Fix reduction axis bug
Fix reduction axis bug

laysakura/chainer,niboshi/chainer,hidenori-t/chainer,niboshi/chainer,Kaisuke5/chainer,muupan/chainer,jnishi/chainer,chainer/chainer,ytoyama/yans_chainer_hackathon,ktnyt/chainer,sinhrks/chainer,benob/chainer,kashif/chainer,keisuke-umezawa/chainer,chainer/chainer,chainer/chainer,aonotas/chainer,ikasumi/chainer,okuta/chainer,AlpacaDB/chainer,AlpacaDB/chainer,wkentaro/chainer,ktnyt/chainer,ysekky/chainer,okuta/chainer,pfnet/chainer,t-abe/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,kikusu/chainer,masia02/chainer,delta2323/chainer,benob/chainer,truongdq/chainer,cupy/cupy,tigerneil/chainer,hvy/chainer,umitanuki/chainer,wkentaro/chainer,ktnyt/chainer,kiyukuta/chainer,keisuke-umezawa/chainer,hvy/chainer,keisuke-umezawa/chainer,ktnyt/chainer,hvy/chainer,tscohen/chainer,chainer/chainer,t-abe/chainer,sinhrks/chainer,cemoody/chainer,cupy/cupy,minhpqn/chainer,cupy/cupy,truongdq/chainer,kikusu/chainer,keisuke-umezawa/chainer,anaruse/chainer,muupan/chainer,tkerola/chainer,yanweifu/chainer,niboshi/chainer,cupy/cupy,wkentaro/chainer,jnishi/chainer,jnishi/chainer,sou81821/chainer,ronekko/chainer,rezoo/chainer,niboshi/chainer,hvy/chainer,okuta/chainer,1986ks/chainer