trident make a damage when ender dragon in the middle (throw only)

this bug i found in 1.2.14/1.2.20.1 (beta) (until 1.8 right now)

when ender dragon in the middle (we cannot shoot or throw anything to dragon, just like wither when have a armor) when i throw my trident into a dragon, a trdent make a damge to dragon.

but in java, dragon dont take any damage when throw.

Update : I report this nearly 1 month (it already 1 month) why dont fix this bug?