With the new feature in 1.8, Ctrl and Mid-Click will take the NBT data from a block when it is picked up as well. That does not work with any type of entity, such as custom geared mobs or command block minecarts. It works with regular blocks though.
Linked issues
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Basically a specific instance of MC-48742.
Should be linked?
I think it just doesn't work with any entities. I guess ill update the post!
Can confirm