[Script] Unused shiny script in Pokecrystal disassembly

[jordanar18]

I'm trying out the unused shiny script in the Pokecrystal disassembly and getting strange results. The script is supposed to make it so that about 1 in 50 encounters is shiny. This is the script:

Unused_CheckShininess:
; Return carry if the DVs at hl are all 10 or higher.

; Attack
	ld a, [hl]
	cp 10 << 4
	jr c, .NotShiny

; Defense
	ld a, [hli]
	and $f
	cp 10
	jr c, .NotShiny

; Speed
	ld a, [hl]
	cp 10 << 4
	jr c, .NotShiny

; Special
	ld a, [hl]
	and $f
	cp 10
	jr c, .NotShiny

.Shiny:
	scf
	ret

.NotShiny:
	and a
	ret

The code as-is does not work, as I ran over 100 encounters and none were shiny.

I replaced all the 10s with 0s, and predictably, every encounter was shiny.

I replaced the 10s with 2s, which is more than half of the encounters. Only a small percentage was shiny, but every encounter played the shiny animation.

What's up?