There's nothing we can do here. APT needs read access to all sources.list, configuration, and preferences files. Marking a sources.list file as unreadable is not supported, and useless, as the cache and /var/lib/apt/lists/ will contain the data from the repository anyway.
There's nothing we can do here. APT needs read access to all sources.list, configuration, and preferences files. Marking a sources.list file as unreadable is not supported, and useless, as the cache and /var/lib/apt/lists/ will contain the data from the repository anyway.