Okay, here's what happens. When you change Link->Jump in a script, he has a tendency to sometimes stop and face upwards for a frame before jumping. For an example, go to this quest, Dmap 2, screen 53, kill the enemies, and move one screen to the right. Compare Link's behavior while holding the right arrow key in builds 846 and 816. In build 816, he progresses smoothly across the screen while bouncing. In build 846, his movement is very choppy. Get my point?
(846) Link Stops Before Jumping
Alright, first of all, here is the link to the quest, the above one does not exist.
Second, it looks like in 863 this bug is fixed, Link moves across the room without stopping like he is does in 819 (or 846 I assume, I never downloaded that build.)
HOWEVER, I did find an interesting bug that does exist in 863 using this quest. You can see it on the very first screen. Just jump, hold a direction button down (any of them) while in the air, and use the sword button. What happens is Link does the "attack" action, but the sword does not appear. I think this may have to do with this fix:
ZScript: Link's sword, Link's hammer, and his wands/candles/canes are now lweapons that can be read and modified with Screen->LoadLWeapon.If so, Link's hammer and wand might have an issue as well. By the way, this bug did not exist in b819, so you can run this quest there if you want to see what it is supposed to do.
A good find! Other bug fixed.