Fixed TypeError when rendering ModelState with multiple bases.
Fixed #21562 -- Warned against using the same app name as a django contrib app.

Thanks yourcelf for the report.
Removed unreachable `else` in `try` block.
Renamed syncdb to migrate in spatialite backend
Fixed #19678 -- GeoDjango test failure with spatialite >= 3.0.

Thanks Julien for the report and Claude for the fix.
Merge pull request #2037 from bmispelon/invalidbaseserror

Fixed TypeError when rendering ModelState with multiple bases.