Wither roses should block all mobs from spawning except wither skeletons from spawning on them, specified in recent changes, however zombie piglins are still spawning on wither roses.

How to reproduce: 

1] Locate a nether fortress in survival

2] Set up a 2 chain of repeating command blocks
> execute @e [type=blaze] ~~~ setblock ~ ~-1 ~ dirt
> kill @e [type=!item] 

3] Fly around and place a wither rose on all dirt blocks

4] find a place where you can watch dirt blocks which is far enough to allow mobs to spawn 

Expected result: Rotten flesh and gold nuggets will be mixed in with the wither skeleton drops and zombie piglins can still be seen spawning