Created by: luotao1

fix https://github.com/PaddlePaddle/PaddleDetection/pull/1507

修改后结果：

2020-09-25 18:39:47,914-INFO: iter: 0, lr: 0.000033, 'loss': '7231.944336', eta: 0:00:00, batch_cost: 0.00008 sec, ips: 103883.69040 images/sec
2020-09-25 18:40:34,280-INFO: iter: 2, lr: 0.000035, 'loss': '2898.865234', eta: 5:10:47, batch_cost: 15.56577 sec, ips: 0.51395 images/sec
2020-09-25 18:41:42,289-INFO: iter: 4, lr: 0.000036, 'loss': '576.639832', eta: 7:26:52, batch_cost: 22.41813 sec, ips: 0.35685 images/sec
2020-09-25 18:42:33,344-INFO: iter: 6, lr: 0.000037, 'loss': '495.023651', eta: 7:08:28, batch_cost: 21.53168 sec, ips: 0.37155 images/sec
2020-09-25 18:43:12,951-INFO: iter: 8, lr: 0.000039, 'loss': '95.421570', eta: 7:26:01, batch_cost: 22.45121 sec, ips: 0.35633 images/sec
2020-09-25 18:44:31,000-INFO: iter: 10, lr: 0.000040, 'loss': '43.708477', eta: 8:12:32, batch_cost: 24.83382 sec, ips: 0.32214 images/sec