Created by: ellinyang

• 标题：mask_rcnn模型预测时报错
• 版本、环境信息：    1）PaddlePaddle版本：paddle1.7.1    2）GPU：nvidia V100, cuda7/cudnn9.0    4）系统环境：Linux 14
• 复现信息： 训练时不固定输入大小，但因业务需要，在导出模型时需固定了输入op的大小为（3, 800, 1344)，故如下代码修改了模型，导致预测时报错。但同样是固定输入大小，faster/cascade rcnn可以顺利infer，但mask_rcnn/retinanet不能，请问是什么原因呢？

  prog.global_block().var(op.name).desc.set_shape(tensor_shape)
      # # 动态infer，修改所有shape
      block_desc = prog.global_block().desc
      for prog_op in prog.global_block().ops:
          prog_op.desc.infer_shape(block_desc)

- 错误日志：
Traceback (most recent call last):
  File "infer_demo.py", line 230, in <module>
    infer(args)
  File "infer_demo.py", line 163, in infer
    return_numpy=False)
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 783, in run
    six.reraise(*sys.exc_info())
  File "/root/miniconda3/lib/python3.7/site-packages/six.py", line 703, in reraise
    raise value
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 778, in run
    use_program_cache=use_program_cache)
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 831, in _run_impl
    use_program_cache=use_program_cache)
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 902, in _run_program
    self._feed_data(program, feed, feed_var_name, scope)
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 580, in _feed_data
    check_feed_shape_type(var, cur_feed)
  File "/root/miniconda3/lib/python3.7/site-packages/paddle/fluid/executor.py", line 230, in check_feed_shape_type
    (var.name, len(var.shape), var.shape, feed_shape))
ValueError: The fed Variable 'image' should have dimensions = 4, shape = (-1, 3, 800, 1344), but received fed shape [1, 3, 1088, 800] on each device