I used this command in a command block:
/summon Item 377 66 297 {Item:{id:minecraft:iron_axe,Count:1,tag:{display:{Name:"Decapitator"},CanDestroy:["minecraft:skull"]}},Age:-32768}
, and in the NBT tags in the bottom of the item tooltip, instead of:
May Break:
Skull
I saw:
May Break:
tile.skull.skeleton.name
This bug may persist in the recent 1.9 snapshots as I haven't tested it, nor have I tested it with other NBT tags.
Linked issues
Comments 1

Confirmed.