Cannot rename a name tag in the anvil

Put the summary of the bug you're having here

What I expected to happen was...:
Rename a name tag that i caught with a fishing rod

What actually happened was...:
when i put it in the anvil it wont allow me to rename 

Steps to Reproduce:
1. get a name tag by fishing

2. Put the name tag in the anvil

3. try rename the name tag