I am not aware of what most of the people customize on their setup.py. What do people use it for in this case?

Couldn't they just edit the template in that case? (Honest question) 
It is just editing a single python script anyway.

Also related, this pull request adds the possibility of adding a distinct settings module per deploy target, I would guess that would cover  many steup.py tuning many people do, but again, I am not sure about what people use it for.

Either way, any suggestion on how this could be added in a more smooth way? I.e. without this impact?