Gazelle? Does anyone know anything about them?

Recieved this Gazelle today, really happy with it. However i noticed a hairline crack through the top headtube lug. The seller did not mention this and i did not see it when i first viewed the images, although now i know it is there it is quite easy to spot.

Really eager to build it up but im unsure how much this would affect the frame. How concerned should i be about the crack?

Is it right in the middle / in the front ?
That's quite a nasty spot.
Don't know if it will hold, but if it breaks, you can fall and get quite serious injuries.
But it can be welded quite easily at that place. Paint needs spot repair afterwards of a complete respray (would be a shame).

Sometimes (older frames with longer lugs) there's a crack in the points of the head lugs where go over the t/t or d/t.
The reason for that is: the points are welded to the rest of the lugs.
If that is the case and there's a crack at that spot, it's not serious. As long as it doesn't go further in the tubes, but that will normally not happen.

Not nice of the crack of course, but still a very pretty frameset.