Internal error depending on mypy_path in setup.cfg file

[demmerichs]

• Are you reporting a bug, or opening a feature request?

  Bug

• Please insert below the code you are checking with mypy,
  or a mock-up repro if the source is private. We would appreciate
  if you try to simplify your case to a minimal repro.

  Sadly, I was unable to produce a minimal example and I cannot share my code that easily unfortunatly. So I know that help can be limited, but I have an interesting observation.

• What is the actual behavior/output?

  When I run mypy on a sub-level __init__.py file it throws an internal error depending on the contents of mypy_path in the config file.

• What is the behavior/output you expect?

  At least a behavior that is independent of my changes to the mypy_path as all point to the same path on my system (see details on path structure following).

• What are the versions of mypy and Python you are using?
  Do you see the same issue after installing mypy from Git master?

  I did not try mypy Git master, as the most recent version I am using 0.770 is quite recent. For python I use 3.6.9.

• What are the mypy flags you are using? (For example --strict-optional)

Well, I use --config-file setup.cfg with the following relevant content. Notice the different settings for the mypy_path value. Both point to the same directory, as I execute mypy on the file src/xxsflow/utils/__init__.py from the working directory /lhome/davidj2/code/sync/space_and_deformable_time:

[mypy]
mypy_path = ./src   # <- this is the setting that produces the INTERNAL ERROR
#mypy_path = /lhome/davidj2/code/sync/space_and_deformable_time/src:./src  # <- no error (except for valid type errors)
namespace_packages = True

[mypy-numpy]
ignore_missing_imports = True
[mypy-tensorflow.*]
ignore_missing_imports = True
[mypy-pptk]
ignore_missing_imports = True
[mypy-scipy.*]
ignore_missing_imports = True
[mypy-psutil]
ignore_missing_imports = True

• If mypy crashed with a traceback, please paste
  the full traceback below.

src/xxsflow/utils/__init__.py:54: error: INTERNAL ERROR -- Please try using mypy master on Github:
https://mypy.rtfd.io/en/latest/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 0.770
Traceback (most recent call last):
  File "mypy/checker.py", line 401, in accept
  File "mypy/nodes.py", line 1062, in accept
  File "mypy/checker.py", line 2011, in visit_assignment_stmt
  File "mypy/checker.py", line 2073, in check_assignment
  File "mypy/checker.py", line 2246, in check_compatibility_all_supers
  File "mypy/checker.py", line 2311, in check_compatibility_super
  File "mypy/checker.py", line 4494, in check_subtype
  File "mypy/checker.py", line 4767, in fail
  File "mypy/messages.py", line 180, in fail
  File "mypy/messages.py", line 165, in report
  File "mypy/errors.py", line 319, in report
  File "mypy/errors.py", line 350, in add_error_info
  File "mypy/errors.py", line 322, in _add_error_info
AssertionError: 
src/xxsflow/utils/__init__.py:54: : note: use --pdb to drop into pdb

Any help and follow-up questions are appreciated!

[hauntsaninja]

Closing, since there isn't a repro. Please re-open if you have something shareable. Fwiw, we fixed things that could cause this in #4881 / #7510