nametag wouldn't work properly.

i was working on an enderman farm which required an endermite with a nickname so it doesn't despawn. i got out my nametag and put it in an anvil, but it wouldn't let me change the name.

What I expected to happen was...:
to be able to change the name on the nametag.

What actually happened was...:
i couldn't alter the name of the nametag or even type anything when i put the nametag in the anvil.

Steps to Reproduce:
1. get an anvil, whether that means crafting it or just opening the creative inventory, and place it down.
2. grab a nametag, either from a dungeon or creative inventory.
3. put the nametag inside of the anvil and try to begin typing.