Update train.py

train.py

@@ -47,7 +47,7 @@ def data_generator(annotation_lines, batch_size, input_shape, anchors, num_class
             if mosaic:
                 if flag and (i+4) < n:
                     image, box = get_random_data_with_Mosaic(annotation_lines[i:i+4], input_shape)
-                    i = (i+1) % n
+                    i = (i+4) % n
                 else:
                     image, box = get_random_data(annotation_lines[i], input_shape, random=random)
                     i = (i+1) % n