A fuss that, on the surface, has to do with the East Hampton Library’s request to hold its Authors Night fund-raiser and children’s fair on town-owned land in Amagansett has riled a certain subset of old line Democrats. But the ire may be payback directed at Town Supervisor Peter Van Scoyoc, who the objectors see as the main force behind the nomination of David Lys, a former registered Republican, to fill a town board seat and run for election as a Democrat in November.