add an option to blacklist .db.sig
pacman asks pacman2pacman to download .db.sig files, which Parabola does not use. This creates error messages that worry users.
It would be nice to add an optional config setting to make it return instantly and silently when asked to download a .db.sig file.
It must be an optional setting so that it can be changed in future and so that pacman2pacman can be used in other Arch-derivatives.