I've not got the scene open, but when I get chance I'll test it with the default corona sun/sky, because I'm pretty sure the effect disappeared when I ran that test at the time, which is what prompted me to post the screenshot.
I'd understand your thought process if the resulting rendered tree(s) has visible square holes, but they don't?
Also if anyone can post a real world example of this happening, that would clear a lot of the doubts up.