Fix concat_examples test for Windows
Fix concat_examples test for Windows

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