Related models in migration state are sometimes strings and not models

[Markus Holtermann]

In some edge cases, I think, related models in the migration state are referenced via strings rather than __fake__ models. This is related to #23745 and 1aa3e09c2043c88a760e8b73fb95dc8f1ffef50e

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/markus/Coding/django/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/home/markus/Coding/django/django/core/management/__init__.py", line 330, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/markus/Coding/django/django/core/management/base.py", line 390, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/markus/Coding/django/django/core/management/base.py", line 444, in execute
    output = self.handle(*args, **options)
  File "/home/markus/Coding/django/django/core/management/commands/migrate.py", line 213, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/home/markus/Coding/django/django/db/migrations/executor.py", line 73, in migrate
    state = self.unapply_migration(state, migration, fake=fake)
  File "/home/markus/Coding/django/django/db/migrations/executor.py", line 127, in unapply_migration
    state = migration.unapply(state, schema_editor)
  File "/home/markus/Coding/django/django/db/migrations/migration.py", line 135, in unapply
    operation.state_forwards(self.app_label, project_state)
  File "/home/markus/Coding/django/django/db/migrations/operations/models.py", line 53, in state_forwards
    list(self.managers),
  File "/home/markus/Coding/django/django/db/migrations/state.py", line 39, in add_model
    self.reload_model(app_label, model_name)
  File "/home/markus/Coding/django/django/db/migrations/state.py", line 61, in reload_model
    self._reload_one_model(rel_model._meta.app_label, rel_model._meta.model_name)
AttributeError: 'str' object has no attribute '_meta'

I've yet to figure out when this is happening exactly.