This is actually already fixed in the snapshots for 1.16 from what I've seen. It is highly doubtful it will be retroactively fixed, but you'll at least have the 1.16 bug fix for this one to look forward to.
This bug still exists in 20w18a, I still wanna put a turtle shell on one.
Was about to report this bug myself, but guess now I don't need to. I really want to give a turtle shell helmet to one of them, I dig the way they look. Would be nice if this bug was patched in next snapshot so I can give my piglin bud a shellmet.
That's not a bug