TestPixletEditorHostDefaultsButDoesNotOverride patched subprocess.Popen for
the whole request. When the captive-portal before_request hook's 30s AP-mode
cache had expired, its `systemctl is-active hostapd` check went through
subprocess.run, got the fake process, and raised TypeError (run() uses the
process as a context manager): a 500 instead of 200. Seen on the Python 3.13
job; reproduced locally by forcing the cache to expire. Other calls now reach
the real Popen.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>