It won't if it cracks in the same place as you'll have dramatically changed the grain structure in that area of the frame.  I am resisting un heat treated aluminium is as brittle as glass speach again. 

Its your call, and it might be fine, I'm trying to give you the benefit of my experience and erring on the side of safety.  Its your headtube FFS, no part of the frame is more important to you or your health and any weakness there is not a good thing.