adobe illustrator - Pathfinder bug - doesn't cut the exact path

I've been trying to go through a basic tutorial.
When I get to Step 7 (of creating the main two shapes), I need to use pathfinder to intersect between two shapes. But the intersect function's outcome is not exact (and actually other pathfinder functions.) I believe it's a bug.

This is how it looks with maximum zoom before the intersection:
And This is how it looks with maximum zoom after the intersection:

You can clearly see that the intersection wasn't made where the exact path of the yellow shape was, but a little bit downwards of that.

Here's two .ai files that correspond to both states for you to download: Before and After.

Answer

You can increase the precision of pathfinder from the hamburger menu. This will alleviate the problem a bit.

So if you set a smaller value into the setting you will get a closer match. However, please note that this will keep happening in many cases if you zoom close enough. It is a unfortunate side effect of how the rendering happens. For it not to really even begin to happen you should also add a point to the underlying shape. Which is why shape builder keeps adding those damn points. It is the correct thing to do in your case, but damn i dont always want to do what they think i am doing ;) So one can not always win.