The frontwheel is also totally toasted btw.
Trying to get a refund from the seller as we speak, but he's not showing any sign of collaboration, says the advice given to me by my LBS (i.e. NOT to ride the bike) is flawed because they want to sell more pieces, etc.
The ad mentioned a bike with no real damage but mentioned a necessary tuning for the wheels and the shifters. Since I'd been looking for this frame for a long time and I didn't want to lose it, I bought it without inquiring any further. Lesson learned. Now I'm trying to get a full refund (I'd reship it to him) or at least a partial refund which would then allow me to cover my losses by selling the tricolor group, the Greg-Lemond-style handlebar and the saddle.