typing.get_origin behaves differently between standard collections and typing collections

Bug report

typing.get_origin behaves differently between standard collections, and typing collections
more specifically

get_origin(dict) is None, while get_origin(Dict) is <class 'dict'>
the same holds for other collections as well

This is true from python3.9 where support for standard collections was added

to my understanding dict should be able to be a drop-in replacement for Dict, which is not true in case relying on get_origin

I suggest updating get_origin to return the relevant class for builtin collections as opposed to None which returns today

note, this might mean a breaking change, as pointed out here, but id does make Dict and dict behave more similarly

Comece reproduzindo typing.get_origin para dict, Dict e os outros pares de coleções descritos no relatório. Leia a implementação existente de get_origin e seus testes; em seguida, revise a discussão sobre o risco de uma alteração incompatível. Considera-se concluído quando o comportamento pretendido estiver acordado e os casos relevantes de coleções estiverem cobertos de forma consistente.