refine test_detection, test=develop

Author: jerrywgz

python/paddle/fluid/tests/test_detection.py

@@ -476,7 +476,7 @@ def test_multiclass_nms(self):
             bboxes = layers.data(
                 name='bboxes', shape=[-1, 10, 4], dtype='float32')
             scores = layers.data(name='scores', shape=[-1, 10], dtype='float32')
-            output = layers.multiclass_nms(bboxes, scores, 0.3, 400, 0.7, 200)
+            output = layers.multiclass_nms(bboxes, scores, 0.3, 400, 200, 0.7)
             self.assertIsNotNone(output)