I noticed a change in behavior between versions 0.720 and 0.730 when using pkgutil-style namespace packages.

For the following __init__.py file:

__path__ = __import__('pkgutil').extend_path(__path__, __name__)

mypy == 0.720 will report:

$ mypy --version
mypy 0.720

$ mypy --show-traceback __init__.py
__init__.py:2: error: Cannot determine type of '__path__'

Thus, I "resolved" this with the following in, in 0.720:

from typing import Iterable
__path__ = __import__('pkgutil').extend_path(__path__, __name__)  # type: Iterable[str]

With mypy ==0.730, I get the following:

$ mypy --version
mypy 0.730

mypy --show-traceback __init__.py
__init__.py:2: error: Module has no attribute "extend_path"
Found 1 error in 1 file (checked 1 source file)

When researching this issue, #7501 (comment) indicates that __import__ is not followed. However, I don't fully understand the change in behavior and had trouble using git-bisect to narrow it down.