Bucket of Lava creates Infinite Fuel Source in Furnace

When putting a lava bucket in the fuel source slot of a furnace it yields fuel infenitly and dosent burn out.

What I expected to happen was...:
Smelting 64 Cobblestone and finding the furnace without fuel.

What actually happened was...:
Found 64 "smooth" stone with fuel at 100%

Steps to Reproduce:
1. Put down a furnace
2. Fill bucket with Lava
3. put bucket of lava in furnace
4. fuel level dosnt run out.