Is that a crack in where the bottom head tube lug meets the downtube? Looks like a bit of a ripple also, as if maybe it's been in a front-end collision?

I don't think it's a Motobecane, I don't recall ever seeing one w/Gipiemme dropouts at this level.

I get the impression you may be in Europe, can you give us an idea where? It may help nail down a more-localized name, in case maybe it's tied to a specific shop or something.