RuntimeWarning in schema tests about reloading models

[Tim Graham]

Warning should be fixed or silenced.

$ python -Wall runtests.py schema

/home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
./home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
..../home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localauthorwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
.sss/home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localauthorwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
./home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
./home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
/home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_uniques.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
./home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_tags.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
/home/tim/code/django/django/db/models/base.py:279: RuntimeWarning: Model 'localbookwithm2m_uniques.schema' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  new_class._meta.apps.register_model(new_class._meta.app_label, new_class)

There is also one warning on the stable/1.7.x branch.

Also:

$ python -Wall runtests.py migrations.test_state
/home/tim/code/django/tests/migrations/test_state.py:450: RuntimeWarning: Model 'a.something' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  class A(models.Model):
/home/tim/code/django/tests/migrations/test_state.py:454: RuntimeWarning: Model 'b.something' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  class B(models.Model):
....../home/tim/code/django/tests/migrations/test_state.py:497: RuntimeWarning: Model 'a.something' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.
  class A(models.Model):

[Tim Graham]

PR

[Markus Holtermann]

Patch looks sensible to me, given the tests pass and the runtime warning(s) is/are gone.

[Tim Graham <timograham@…>]

In f5da438:

Fixed #24812 -- Fixed app registry RuntimeWarnings in schema and migrations tests.

[Tim Graham <timograham@…>]

In 3c0e03ef:

[1.8.x] Fixed #24812 -- Fixed app registry RuntimeWarnings in schema and migrations tests.

Backport of f5da4380723c93998a4f5a845b6f26fa51a2cfe1 from master