As I couldn't scan anymore after recent updates, I had the surprise that even with my make.conf containing USE="scanner", it's not taken by emerge. emerge --info gives "scanne" without "r". So, when I do : USE="scanner" emerge -DauN world, it gives me to recompile media-video/mediainfo and media-video/mediainfo. And if I add : media-libs/libmediainfo scanner media-video/mediainfo scanner in package.use, emerge -DauN world wants to recompile them too. Sorry for my bad english But, all of this didn't help me recovering scan by network...
Sorry, that was just stupid. media-video/mediainfo-0.7.96 and media-libs/libmediainfo-0.7.96 was just my today update. Nothing about scanner. And the only package use scanner USE is wine. I don't understand why I can't scan anymore...