Swimming players have an incorrect hitbox

Player's that are swimming have an incorrect hitbox, though the camera height still changes correctly

Steps to Reproduce
*Make a 1 block gap
*Go into water and try to swim into it

Observed Results
*You can't go into the 1 block gap while swimming(you can't even swim at the very top of a block on the ceiling)

Expected Results
*You can go into a 1 block gap while swimming

(In short, you can't crawl and swim through 1 block gaps)