Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

Is there anything that is currently blocking this patch? I'd quite
like it to get into PG16.

Especially since I ran into another use case that I would want to use
this patch for recently: Adding an async cancel function to Python
it's psycopg3 library. This library exposes both a Connection class
and an AsyncConnection class (using python its asyncio feature). But
one downside of the AsyncConnection type is that it doesn't have a
cancel method.

I ran into this while changing the PgBouncer tests to use python. And
the cancellation tests were the only tests that required me to use a
ThreadPoolExecutor instead of simply being able to use async-await
style programming:
https://github.com/pgbouncer/pgbouncer/blob/master/test/test_cancel.py#LL9C17-L9C17