`apt update` doesn't return non-zero on error unless you set `APT::Update::Error-Mode=any`, apparently. We might want to set that in OverrideSourcesList, where we also set `Acquire::Retries=3`.
`apt update` doesn't return non-zero on error unless you set `APT::Update: :Error- Mode=any` , apparently. We might want to set that in OverrideSources List, where we also set `Acquire: :Retries= 3`.