grindstone exploit

[mrcoffee1026]

Enchant an item with the enchantment table... then place item in grindstone. The grindstone removes... ONLY VANILLA enchants, leaving all emerald enchants in place. At that point it can be enchanted again, and again, and again using the same method until every available emerald enchant is applied to this item.

Unrelated but true: Unluck cannot be disabled.

[MinecraftAdmin]

Wow, this issue is old. Would appreciate a fix!