Debian 5.0 Lenny is deprecated and now hosted at archive.debian.org
Without this fix installing Debian 5.0 requires manual intervention: acknowledging "repo not found" warnings and changing /etc/apt/sources.list after install.
(separated from pull request #358 and rebased on top of recent commits)
Debian 5.0 repos now live in archive.debian.org
Debian 5.0 Lenny is deprecated and should not be used.
(Useful for testing belated upgrades though.)