transaction.atomic is incompatible with ExitStack().enter_context

[flaeppe]

Bug report

django.db.transaction.atomic is incompatible with contextlib.ExitStack().enter_context

What's wrong

Repro case:

from contextlib import ExitStack
from django.db import transaction

with ExitStack() as stack:
    stack.enter_context(transaction.atomic())

Causes:

error: Argument 1 to "enter_context" of "ExitStack" has incompatible type "Atomic"; expected "ContextManager[<nothing>]"  [arg-type]

How is that should be

transaction.atomic() should be accepted as a valid argument to stack.enter_context as it declares the expected __enter__ and __exit__ methods.

System information

• OS:
• python version: 3.8.0
• django version: 3.0.7
• mypy version: 0.770
• django-stubs version: 1.5.0

[flaeppe]

Closed via #909