The problem here is that `AbstractUser` has an email field on it, but it's not unique. The choices come down to:

1. Copy and Paste `AbstractUser` and change as needed.
2. Use this somewhat cryptic, dynamic approach.

Inheriting `AbstractBaseUser, PermissionMixin` and copy pasting code from `AbstractUser` seemed way worse.

It might be more readable if done like this:
```python
email_field, _, _, _ = User._meta.get_field_by_name('email')
email_field._unique = True
```