Don't require pygraphviz for regenerate.sh (#17485)
Summary:
closes #17336
Do not overwrite config.yml if script throws an error
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17485
Differential Revision: D14604388
Pulled By: kostmo
fbshipit-source-id: 5024545e3a8711abdbc0800911c766929dbca196
