Something bad has happened with graph! Data node "Preprocessor/mul" has 2 producers

1. The entire URL of the file you are using

/content/models/research/object_detection/model_main.py

2. Describe the bug

A change made on July 1, 2020 broke OpenVino blob convert for object detection mobilenetssdv2
Error is not present if before training I switch to commit hash 58d19c67e1d30d905dd5c6e5092348658fed80af before training

3. Steps to reproduce

This notebook shows the issue under the convert section

4. Expected behavior

The convert stage should show:

[ SUCCESS ] Generated IR version 10 model.
[ SUCCESS ] XML file: /content/models/research/fine_tuned_model/./IR_V10_fruits_mnssdv2_6k/frozen_inference_graph.xml
[ SUCCESS ] BIN file: /content/models/research/fine_tuned_model/./IR_V10_fruits_mnssdv2_6k/frozen_inference_graph.bin
[ SUCCESS ] Total execution time: 25.72 seconds. 
[ SUCCESS ] Memory consumed: 1940 MB. 

5. Additional context

Convert log failure when using HEAD:

/content/models/research/fine_tuned_model
[setupvars.sh] OpenVINO environment initialized
[ WARNING ]  Use of deprecated cli option --tensorflow_use_custom_operations_config detected. Option use in the following releases will be fatal. Please use --transformations_config cli option instead
Model Optimizer arguments:
Common parameters:
	- Path to the Input Model: 	/content/models/research/fine_tuned_model/frozen_inference_graph.pb
	- Path for generated IR: 	/content/models/research/fine_tuned_model/./IR_V10_fruits_mnssdv2_6k
	- IR output name: 	frozen_inference_graph
	- Log level: 	ERROR
	- Batch: 	Not specified, inherited from the model
	- Input layers: 	Not specified, inherited from the model
	- Output layers: 	Not specified, inherited from the model
	- Input shapes: 	Not specified, inherited from the model
	- Mean values: 	Not specified
	- Scale values: 	Not specified
	- Scale factor: 	Not specified
	- Precision of IR: 	FP16
	- Enable fusing: 	True
	- Enable grouped convolutions fusing: 	True
	- Move mean values to preprocess section: 	False
	- Reverse input channels: 	True
TensorFlow specific parameters:
	- Input model in text protobuf format: 	False
	- Path to model dump for TensorBoard: 	None
	- List of shared libraries with TensorFlow custom layers implementation: 	None
	- Update the configuration file with input/output node names: 	None
	- Use configuration file used to generate the model with Object Detection API: 	/content/models/research/fine_tuned_model/pipeline.config
	- Operations to offload: 	None
	- Patterns to offload: 	None
	- Use the config file: 	/opt/intel/openvino/deployment_tools/model_optimizer/extensions/front/tf/ssd_v2_support.json
Model Optimizer version: 	2020.1.0-61-gd349c3ba4a
The Preprocessor block has been removed. Only nodes performing mean value subtraction and scaling (if applicable) are kept.
[ ANALYSIS INFO ]  Your model looks like TensorFlow Object Detection API Model.
Check if all parameters are specified:
	--tensorflow_use_custom_operations_config
	--tensorflow_object_detection_api_pipeline_config
	--input_shape (optional)
	--reverse_input_channels (if you convert a model to use with the Inference Engine sample applications)
Detailed information about conversion of this model can be found at
https://docs.openvinotoolkit.org/latest/_docs_MO_DG_prepare_model_convert_model_tf_specific_Convert_Object_Detection_API_Models.html
[ ERROR ]  Exception occurred during running replacer "REPLACEMENT_ID" (<class 'extensions.front.ChangePlaceholderTypes.ChangePlaceholderTypes'>): Something bad has happened with graph! Data node "Preprocessor/mul" has 2 producers

6. System information

Google Colab Notebook using:

%tensorflow_version 1.x
!pip install tf_slim