Error while converting op of type: BatchNormalization. Error message: provided number axes -1 not supported

[daylight0998]

🐞Describe the bug

(1) I try to convert onnx model to mlmodel, but it's error:
Error while converting op of type: BatchNormalization. Error message: provided number axes -1 not supported

Trace

Traceback (most recent call last):
File "/Applications/PyCharm.app/Contents/helpers/pydev/pydevd.py", line 1741, in
main()
File "/Applications/PyCharm.app/Contents/helpers/pydev/pydevd.py", line 1735, in main
globals = debugger.run(setup['file'], None, None, is_module)
File "/Applications/PyCharm.app/Contents/helpers/pydev/pydevd.py", line 1135, in run
pydev_imports.execfile(file, globals, locals) # execute the script
File "/Applications/PyCharm.app/Contents/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
exec(compile(contents+"\n", file, 'exec'), glob, loc)
File "/Users/vipkid/PycharmProjects/ai/ai-teacher/apps/landmark_to_image/onnx_to_mlModel.py", line 27, in
minimum_ios_deployment_target='13')
File "/Users/vipkid/anaconda3/lib/python3.7/site-packages/onnx_coreml/converter.py", line 627, in convert
_convert_node_nd(builder, node, graph, err)
File "/Users/vipkid/anaconda3/lib/python3.7/site-packages/onnx_coreml/_operators_nd.py", line 2395, in _convert_node_nd
return converter_fn(builder, node, graph, err)
File "/Users/vipkid/anaconda3/lib/python3.7/site-packages/onnx_coreml/_operators_nd.py", line 349, in _convert_bn
err.unsupported_op_configuration(builder, node, graph, "provided number axes {} not supported".format(rank))
File "/Users/vipkid/anaconda3/lib/python3.7/site-packages/onnx_coreml/_error_utils.py", line 62, in unsupported_op_configuration
self.rerun_suggestion)
TypeError: Error while converting op of type: BatchNormalization. Error message: provided number axes -1 not supported
Please try converting with higher minimum_ios_deployment_target.
You can also provide custom function/layer to convert the model.

it may be a break at the name of BatchNormalization_31, the input[0] rank name is -1

To Reproduce

• If a python script can reproduce the error, please paste the code snippet

(2) convert onnx model to mlmodel code is:
import os
import onnx
from onnx import onnx_pb
from onnx_coreml import convert

dataset_dir = "./"

model_in = os.path.join(dataset_dir, "model.patched.onnx")
model_out = os.path.join(dataset_dir, "vgnet.mlmodel")
model_file = open(model_in, 'rb')
model_proto = onnx_pb.ModelProto()
model_proto.ParseFromString(model_file.read())
print("prepare to convert...")
model = onnx.load_model('vgnet.onnx')
coreml_model = convert(model_proto,
minimum_ios_deployment_target='13')

-  attach ONNX model.png
![model patched onnx(2)](https://user-images.githubusercontent.com/5449858/82629368-18603200-9c22-11ea-96d7-d59c2bd0364a.png)


## System environment (please complete the following information):
 - coremltools version  (e.g., 3.0b5): 3.3
    onnx: 1.6.0
 - onnx-coreml version (e.g. 1.0b2): 1.3
 - OS (e.g., MacOS, Linux): MacOS
 - macOS version : 10.15.4
    install python: anaconda
 - python version: 3.7
 - torch version: 1.5.0

## I  had us the following code to convert model:

import onnx
import onnx.helper
import onnx.shape_inference

model = onnx.load("./vgnet.onnx")

# Add graph input for each initializer
existing_inputs = {v.name for v in model.graph.input}
model.graph.input.extend([
    onnx.helper.make_tensor_value_info(
        name = tensor.name,
        elem_type = tensor.data_type,
        shape = list(tensor.dims),
    )
    for tensor in model.graph.initializer
    if tensor.name not in existing_inputs
])

# Check if it passes shape inference now
onnx.shape_inference.infer_shapes(model)

# Save the resulting model
onnx.save(model, "model.patched.onnx")

[daylight0998]

What can be done to resolve this error？