django auth: increasing max_length group name field
Short answer: I don't think that it is possible.
You probably need to extend the model if you want to change anything on it.

You could go into the source of the Django lib (probably located in your python installation somewhere in site-packages/) and make the change there and then make migrations, but that is generally a bad idea since it will cause you troubles when trying to update to a newer Django version later on. And it will even be worse if you need to deploy the code on other machines.
Some IDEs will even prevent modifications on files from external libs (for example, the Django files in site-packages/) to protect developers from themselfs.
In Django 1.8 the max_length of name field for Group model in the auth app is by default 80 characters.
I need to increase this limit without extending the default group model.