My previous attempt (patching check_for_updates) still lost the race:
the background update-check thread captures check_for_updates via
global lookup at call time, but on CI the thread was already past that
point (mid-git-fetch) by the time the test's patch took effect. The
real fetch returned 4954 commits-behind and wrote that to
banner._update_result before the test's assertion ran.
Fix: test what we actually care about — that get_update_result respects
its timeout parameter — and drop the asserting-on-result-value that
races with legitimate background activity. The get_update_result
function's job is to return after `timeout` seconds if the event isn't
set. The value of `_update_result` is incidental to that test.
Validation: tests/hermes_cli/test_update_check.py now 9/9 pass under
CI-parity env, and the test no longer has a correctness dependency on
module-level state that other threads can write.
b2f8e231dd