From dfdb03cc1720639e390f6d3aba2d3e8dd3861c3a Mon Sep 17 00:00:00 2001
From: Yang Wang <tiandiwoxin@icloud.com>
Date: Thu, 13 Jul 2017 23:29:36 -0700
Subject: [PATCH] fix concat when the dimension concatenated along is larger
 than 2 (#1230)

* fix concat when dim >= 3

* fix backward

* fix backward

* changing back to tensor copy

* meet code review