Wrong catenation type leads to model exportation failure [TF2 + object detection]

Prerequisites

Please answer the following questions for yourself before submitting an issue.

• I am using the latest TensorFlow Model Garden release and TensorFlow 2.
• I am reporting the issue to the correct repository. (Model Garden official or research directory)
• I checked to make sure that this issue has not already been filed.

1. The entire URL of the file you are using

https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/tf2_detection_zoo.md

2. Describe the bug

I was following the official TF2 object detection tutorial. However, I failed to export the trained model. The issue seems to be that tensorflow used '/' instead of '' when creating some temporary file.

3. Steps to reproduce

the official TF2 object detection tutorial. I was using the pre-trained model "faster_rcnn_resnet101_640x640".

4. Expected behavior

successfully export the trained model

5. Additional context

6. System information

• Windows 10 Enterprise
• TensorFlow installed from (source or binary): Anaconda 3
• TensorFlow version (use command below): 2.3.0
• Python version: 3.8.3
• Bazel version (if compiling from source):
• GCC/Compiler version (if compiling from source):
• CUDA/cuDNN version: 10.1
• GPU model and memory: GeForce GTX 1660, 6 GB GDDR5