sasha, that frame had super tight clearances. my guess, and this is only a guess, *the fork gave when it hit the pothole like all forks will and should do.......
*Uhhh, I don't think so! Cino Cinelli would argue that the fork is the most vital part of the frameset, and that it should be more bullet-proof than the rest of the frame ("The Custom Bicycle",Mike Kolin & Denise de la Rosa, 1979). That said, he was careful to eliminate the pointed end of the lower head lug tang so that it wouldn't act like a can opener on the bottom of the down tube when potholes were encountered.
Nor Meyer, Mt. Vernon, IA