Incorrect Manager type for child model's objects when parent has circular imports

[syastrov]

After running on an internal codebase, where we have a few places using inherited models, I encountered some issues in figuring out the correct Manager type for an inherited Model (which otherwise works great!), when there is an import cycle.

I created a relatively small testcase that demonstrates the problem:

[CASE managers_multiple_inheritance_multiple_files_import_cycle]
from django.db import models
from myapp.models import Child
reveal_type(Child.objects) # E: Revealed type is 'django.db.models.manager.Manager[myapp.models.child.Child]'
Child.objects.create(c=True, p="abc", other_id=123)

[file myapp/__init__.py]
[file myapp/models/__init__.py]
from .other import Other
from .parent import Parent
from .child import Child

[file myapp/models/other.py]
from django.db import models
class Other(models.Model):
    o = models.CharField(max_length=255)

[file myapp/models/parent.py]
from django.db import models
from myapp.models import Other
# Changing the above line to the following fixes around the problem:
#from myapp.models.other import Other
class Parent(models.Model):
    p = models.CharField(max_length=255)
    other = models.ForeignKey(Other, on_delete=models.CASCADE)

[file myapp/models/child.py]
from django.db import models
from myapp.models import Parent
class Child(Parent):
    c = models.BooleanField(default=True)

reveal_type(Child.objects) gives: Revealed type is 'django.db.models.manager.Manager[myapp.models.parent.Parent]'
But it should be django.db.models.manager.Manager[myapp.models.child.Child].

If I change the line from myapp.models import Other to from myapp.models.other import Other in myapp/models/parent.py, then it behaves as expected, so there is a fairly easy workaround.

I don't know if this is something to do with mypy itself or how this plugin works.

[flaeppe]

I can't reproduce this, feel free to reopen with a breaking case