Button pins and read_digital

I was researching something regarding microbit pins. I found an up coming feature that button pins (5 & 11) were reusable as read_digital pins.
It may be the case, i didn't read all the source.
Once `pinX.set_pull` or `pinX.read_digital` has run on pin 5/11 then it should now throw an exception if `button_a` or `button_b` methods such as `.is_pressed()` is used.