This is a nice improvement that maybe ought to be called out in the commit message? (If you agree I can handle that when I merge it.)

Isn't this done by default? I see the same traceback with and without this on this example:

import asyncio

async def func():
    await asyncio.sleep(1)

async def main():
    async with asyncio.timeout(0.1):
        await func()

asyncio.run(main())

Not quite. When using raise exc from ... the CancelledError instance gets stored in exc.__cause__, while without it, it gets stored in exc.__context__, and the connecting phrase in the output is different:

__cause__:

The above exception was the direct cause of the following exception:

__context__:

During handling of the above exception, another exception occurred:

(If both are set it follows __cause__.

Precicely. I has bothered me for a while that timeouts happen with the latter message, as if somehow, there was an error during exception handling. I wanted to use the opportunity to roll that fix in :)

This is a nice improvement that maybe ought to be called out in the commit message? (If you agree I can handle that when I merge it.)

Thank you, agreed.

Not quite. When using raise exc from ... the CancelledError instance gets stored in exc.cause, while without it, it gets stored in exc.context, and the connecting phrase in the output is different:

Ah, right! I missed that. Adding a test would be nice.

I'll add that in a few hours.