nbdev v2.0.6 was just released, with a great new feature: hooks for Jupyter Notebook and Lab to automatically clean your notebooks each time you save! 
We’ve been testing this internally and have found it to be a much more pleasant experience than the previous git hooks version. Jupyter handles it in the background so your ordinary git commands aren’t slowed down.
How to use
First upgrade nbdev, then install hooks by running nbdev_install_hooks. You can also remove the .gitconfig file in your project directory with the old hooks. See the nbdev_install_hooks docs for more info.
(By the way, you can help us test features like this before they’re released by installing nbdev master branch directly from GitHub.)