This reverts commit e0cc36f615.
The problem is the following:
* With non-gis backends, gis_tests sub apps are not discovered
(see runtests.py)
* Consequently, the app_label is inferred from the gis_tests
AppConfig
* Then models with same names in different sub apps conflict
because of same model_name/app_label pair.
The new signature enables better support for routing RunPython and
RunSQL operations, especially w.r.t. reusable and third-party apps.
This commit also takes advantage of the deprecation cycle for the old
signature to remove the backward incompatibility introduced in #22583;
RunPython and RunSQL won't call allow_migrate() when when the router
has the old signature.
Thanks Aymeric Augustin and Tim Graham for helping shape up the patch.
Refs 22583.
