core: Try next source if previous couldn't resolve a key
core: Try next source if previous couldn't resolve a key

The code was almost correct: there was a comment saying "try next source", but
seems we forgot to execute the "get next source".

MathieuDuponchelle/grilo,grilofw/grilo,MathieuDuponchelle/grilo,kyoushuu/grilo,jasuarez/grilo,jasuarez/grilo,kyoushuu/grilo,GNOME/grilo,GNOME/grilo,kyoushuu/grilo,grilofw/grilo,kyoushuu/grilo,grilofw/grilo,jasuarez/grilo,MathieuDuponchelle/grilo