Rework follow-up on the per-job TERMINAL_CWD readers-writer lock.
The lock was acquired BEFORE the try: whose finally: is the only release
site, with the env-override statements (os.environ[TERMINAL_CWD] = workdir;
logger.info) sitting in the unprotected window between acquire and try. Any
exception there — a raising log handler, an os.environ error, a thread
interrupt — propagated out of run_job WITHOUT running the finally, leaking
the lock. A leaked writer permanently deadlocks the whole scheduler (every
future cron job blocks on acquire_*); a leaked reader blocks all writers.
- Snapshot _prior_terminal_cwd before the acquire (so the finally can always
restore env even if the body raises before the override).
- Open the try: immediately after acquire and move the env-override lines
inside it, so the existing finally always releases the lock.
- Add a mutation-verified regression test: a workdir job whose in-window
logger.info raises must still release the writer lock (a subsequent
acquire_write must not block).
7f71a48a3a