Old generated pigs wearing saddles not being able to be named with a name tag

When you try to name a pig that has a saddle on it with a name tag it gives the pig a name and gives you back the name tag, when you re-log the name above the pig goes away and the name tag stays in your inventory. I tried it in my creative world but it worked fine with newly spawned pigs, but not with the one in my survival world which is from 1.8 or so.

What I expected to happen was for the pig to get a name and for the name tag to go away and not come back.
Describe what you thought should happen here

What actually happened was the pig got a name and the name tag re-appeared in my inventory.

Steps to Reproduce:
1. Generate a world in 1.8.
2. Get a pig with a saddle and a name tag with a name on it.
3. Name the pig with the tag.