### What needs to get done We need something similar to `install_in_root` that can instead rewrite the existing `sources.list` or `ubuntu.sources` file to modify the default repositories. At minimum, it needs to be able to change the repository URL so we can change from, for example, `archive.ubuntu.com` to `old-releases.ubuntu.com`. We need to be able to do this for overlay roots etc., which is why this does not duplicate https://github.com/canonical/craft-providers/issues/771. This can then also be used for doing this to apps in destructive mode. ### Why it needs to get done In order to be able to change the sources for EOL Ubuntu releases.