From Microsoft/vscode-python#588 .
I really don't know if anything can be done since multiprocessing.__init__ is a bit nuts.
Will be resolved once typeshed is properly working. #1096
It's my next goal to get that working.
Seems the issue still there?

VS Code version: 1.32.3
Python Extension version: 2019.2.5558
Python Version: 3.7.1
OS and version: Windows 10 64 educational v1709
It's working on the typeshed branch. It will hopefully be merged, soon.
Working with 0.14.0.
Most helpful comment
It's working on the typeshed branch. It will hopefully be merged, soon.