Apptainer cleans path
Apptainer cleans the path when starting a container, which renders this check: https://gitlab.cern.ch/lhcb-core/LbEnv/-/blob/8cbfaccf8c7e0f31f3107f79b0ba3b24f619d831/python/LbEnv/Bootstrap.py#L181 useless, unfortunately.
Thanks to @cburr for debugging the issue.