Previous attempt (shield + sync invalidate fallback) didn't work
because shield only protects against cancellation from *other* tasks.
When the caller task itself is cancelled mid-query, its next await
re-raises CancelledError as soon as the shielded coroutine yields —
rollback inside session.close() never completes, the aiomysql
connection is orphaned, and the pool logs 'non-checked-in connection'
when GC finally reaches it.
Hand exception-path cleanup to loop.create_task() so the new task
isn't subject to the caller's pending cancellation. close() (and the
invalidate() fallback for a dead connection) runs to completion.
Success path is unchanged — still awaits close() inline so callers
see commit visibility and pool release before proceeding.
anti
fb69a06ab3