[3.13] gh-143378: Fix use-after-free when BytesIO is concurrently mutated during write operations (GH-143408)#143600

serhiy-storchaka wants to merge 1 commit intopython:3.13python/cpython:3.13from

serhiy-storchaka:backport-6d54b6a-3.13serhiy-storchaka/cpython:backport-6d54b6a-3.13Copy head branch name to clipboard