Generator based coroutines were long deprecated and removed and asyncio doesn't not supports it. There is some left over code for supporting it which can be removed now.

The first thing is this behavior of asyncio.iscoroutine which makes no sense now. I propose to remove this first.

import asyncio

def gen():
    yield 1

assert not asyncio.iscoroutine(gen()) # fails

Linked PRs

• GH-102748: remove legacy support for generator based coroutines from asyncio.iscoroutine #102749