accept/recv/send kept the socket RwLock during the syscall. After
fork, the child copied that held lock, so _ResourceSharer._afterfork
hung in listener.close().
Unskip fork connection pickling, pool task ref release, and spawn
thread-pool terminate. Add extra_tests for fork+accept close and
fork after DupFd.
Assisted-by: Grok:4.6
* Fix ctypes from_buffer writes and unskip passing MP tests
Write char-array .value/.raw through borrowed buffers instead of
Cow::to_mut(), which copied shared memory into a private buffer.
Unskip connection pickling, sharedctypes, Condition notify, and
concurrent.futures interpreter-shutdown tests. Cover forkserver
Condition notify and shared ctypes char arrays in extra_tests.
Assisted-by: Grok:4.6
* Unskip linux RLock repr; keep fork pickling hang skip
test_repr_rlock passed on Linux spawn/fork/forkserver. Connection
pickling hangs under the fork start method, so skip it only there.
Build the apple-container image from rust:bookworm; rust:bullseye
apt indexes 404.
Assisted-by: Grok:4.6
Jeong, YunWon