Comment 5 for bug 929382

As the script always exits right away after the trap, the only way that I found to do that cleanly is to add an "exit 0":

undo_network() {
        [...]
        log_failure_msg "Failed to set up LXC network"
        exit 0
}

This allows the package to get configured and not break upgrades even if LXC setup fails for some reason. Does that sound acceptable?