Ride it as is. Frames have surprisingly high resilency, they'll flex to certain point and spring back. It looks like that one flexed to the point of cracking the paint without deforming the tubes.

I had a frame with very noticiable ripples in the metal but the head tube angle was still within 'spec'. I'd venture a guess and say that if you placed a digital angle gauge on the head tube it'd be so close to whatever the original angle was that it wouldnt be worth touching.