Fix testing.parameterized exception for Python 2
Fix testing.parameterized exception for Python 2

ktnyt/chainer,ktnyt/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,jnishi/chainer,ktnyt/chainer,keisuke-umezawa/chainer,jnishi/chainer,niboshi/chainer,rezoo/chainer,okuta/chainer,wkentaro/chainer,jnishi/chainer,ronekko/chainer,okuta/chainer,wkentaro/chainer,keisuke-umezawa/chainer,hvy/chainer,chainer/chainer,keisuke-umezawa/chainer,ktnyt/chainer,hvy/chainer,tkerola/chainer,hvy/chainer,chainer/chainer,anaruse/chainer,keisuke-umezawa/chainer,aonotas/chainer,niboshi/chainer,jnishi/chainer,pfnet/chainer,okuta/chainer,wkentaro/chainer,okuta/chainer,hvy/chainer,niboshi/chainer,chainer/chainer