Cut in my lug

[w1ndh0rse]

I've owned this bike (1977 Schwinn Le Tour III) for about a month. For all I know, this has been there the entire time and I didn't notice it. It looks like someone took a tiny saw or something and cut into the lug. It looks to perfect to be a crack. I'm a novice when it comes to bike repair and I'm looking to learn what this might be. Is it a repair to a crack? Should I be looking for a new frame?

[GeorgeET]

Not good, your steering head is cracking. You can drill a small hole at the end of crack, like a lollipop to stop it from going further. (Take the fork out first and clean well afterwards.) Maybe it can be welded but the paint will be burned. To the left higher up I see a white line is that just paint.