[Bug] wrong non negative exitcode with no result on -Ai

[cartok]

Hi!

I noticed that aura's exit code remains 0 when aura -Ai <package> has no result.

btw: The backup feature is amazing, so thanks! For me it's the way to dodge btrfs or lvm and go straight with xfs even on my workstation. Together with a setup script for linux and git-synced dotfiles - thats all I should need.

[fosskers]

Indeed -Si returns 1 when the package is missing. I think this is an appropriate change.