The "ensure checkout cache" step on LUCI is flaky and causes tree closures. #68328
Description
An example of a failure of this kind is here. The specific error was the following script failing with an unknown error (-9 return):
Executing command [
'/opt/s/w/ir/cipd_bin_packages/vpython',
'-u',
'/opt/s/w/ir/kitchen-checkout/recipe_engine/recipe_modules/file/resources/fileutil.py',
'--json-output',
'/opt/s/w/ir/tmp/t/tmprxrZ52.json',
'ensure-directory',
'--mode',
'0777',
'/opt/s/w/ir/cache/builder',
]