gh-143378: Fix UAF when BytesIO is concurrently mutated during write operations
#178879
| Job | Run time |
|---|---|
| 9s | |
| 0s | |
| 1s | |
| 0s | |
| 0s | |
| 0s | |
| 1s | |
| 1s | |
| 2s | |
| 1s | |
| 1s | |
| 1s | |
| 0s | |
| 1s | |
| 1s | |
| 1s | |
| 0s | |
| 1s | |
| -1s | |
| 20s |