We still utilize a few things in the Django admin UI template and

template tag library for our administration UI. In the upgrade from

Django 1.11 to 3.2, we ended up regressing the ability for extensions to

provide their own change forms.
This was caused by the use of {% prepopulated_fields_js %}, which now

explicitly depends on the opts variable (equivalent to a

Model._meta).
We now only call this if we know we have opts. This shouldn't be a

problem for any extensions, as this is really just supporting a

Django-specific feature.
To avoid other issues, all uses of opts have now been wrapped in an

if check.

Verified that the Review Bot configuration form can once again be used

in Review Board 5.
Verifeid that other change forms are unaffected.