Enchanted Skull won't glimmer when worn

Note that in 1.11 it is possible to obtain enchanted skulls in survival.

When you type this command:

/give @p minecraft:skull 1 1 {ench:[{id:0,lvl:100}]}

it will give you an enchanted wither skull with protection 100. Compared to what this command gives you:

/give @p minecraft:diamond_helmet 1 0 {ench:[{id:0,lvl:100}]}

it gives you a diamond helmet that also has protection 100. When you put the enchanted diamond helmet on your head, it will shimmer. If you put the enchanted wither skull on your head, it will NOT shimmer.

What I thought would happen was: anything that you can wear, (armor, pumpkins, skulls) should shimmer when enchanted and worn