Don't remove `deb-src` for PPA repositories.
Don't remove `deb-src` for PPA repositories.

This commit updates the behaviour of the 'deb-src' revert script so it
only applies to 'deb' commands. When a PPA is being added, the script
failed to recognise this and reverted the install.

StanAngeloff/vagrant-shell-scripts,StanAngeloff/vagrant-shell-scripts