api.updates._schedule_restart() spawns a daemon thread that calls
os.execv() after a short sleep. Tests in test_update_banner_fixes.py
monkeypatch os.execv to a no-op, but monkeypatch teardown can win the
race against the daemon thread — when the thread wakes up after
teardown, the real os.execv is back, and it re-execs pytest with the
original argv. From the outside this looked like pytest hanging at 99%
and then restarting the entire suite from 0% in a loop.
The fix shadows os.execv with a permanent no-op wrapper at conftest
module-import time, so late-firing daemon threads can't escape. Tests
that need to verify execv was called still patch it themselves; their
patches sit on top of the wrapper for their lifetime.
Also adds tests/test_pytest_execv_guard.py to pin the guard against
future conftest refactors.
Hermes Agent