[builder] Roman/Italic variation issue in Indesign when stat in config.yaml

The italic is going back to roman when using the weight slider in Indesign — but only when there is the stat in the config.yaml.

https://user-images.githubusercontent.com/12222436/105488609-2f27be80-5cb2-11eb-945b-be6a06aa88ca.mov

These are my different test:
- When exported as we use too ie. with **gen-stat.py + build.sh** : *no issue*
See: https://github.com/RosaWagner/Texturina/tree/master/fonts/variable
- When exported with **builder + stat entry in config.yaml** : *issue*
See: https://github.com/RosaWagner/Texturina/tree/master/fonts-builder/variable
- When standard font exported with **builder without stat entry in config.yaml**: **no issue**
See: https://github.com/RosaWagner/Archivo/tree/master/fonts/variable