__getnewargs__ for a subclass incompatible with return type of supertype

Here is an example commit with the issue: https://github.com/eli-schwartz/meson/commit/4d204bb81869422a102264611d9aea314a1ac2ca

mypy.ini: https://github.com/mesonbuild/meson/blob/27626124d0bdd89f5f276f70a73b4713aa3aac3d/.mypy.ini

$ mypy --version
mypy 0.961 (compiled: yes)

$ mypy mesonbuild/interpreter/primitives/string.py
mesonbuild/interpreter/primitives/string.py:211:5: error: Return type "Tuple[str, str]" of "__getnewargs__" incompatible with return type "Tuple[str]" in supertype "str"

I subclassed str and treat it specially with its own incompatible __new__() to enforce a specific creation pattern. After discovering I need to pickle it as well, I added a __getnewargs__() which is also incompatible. mypy is happy with my incompatible new, but not with the getnewargs that needs to match the argument contract of new.

Reproduziere den Bericht mit mypy 0.961 unter Verwendung von mesonbuild/interpreter/primitives/string.py und der verlinkten .mypy.ini-Konfiguration. Untersuche, wie die Signaturen von new und getnewargs der Unterklasse im Vergleich zu str geprüft werden, und verifiziere anschließend, dass der vorgesehene pickle-Fall behandelt wird, ohne die gemeldete inkompatible Rückgabediagnose.