CRIT: unattended-upgrades for Wheezy is broken

[Daenney]

The 50unattended-upgrades file we write is completely incompatible with Wheezy.

It should write

Unattended-Upgrade::Origins-Pattern {
        "origin=Debian,archive=stable,label=Debian-Security";
};

But we get:

// Automatically upgrade packages from these (origin:archive) pairs
Unattended-Upgrade::Allowed-Origins {
    "${distro_id}:${distro_codename}-security";
};

Apparently there've been a few changes...

[Daenney]

This currently means that on Debian Wheezy machines the configuration we drop is completely useless and won't cause any security updates to be automatically installed.

I'll submit a PR for this shortly both on master and 1.4.x.