Smoker texture is inconsistent with furnace/dispenser/dropper texture

The bug

Despite being composed of cobblestone like the others, the textures used for smokers are not shaded in the same way as the texture used for dispensers, droppers and furnaces, despite both seemingly being based on the same texture shape (implying that they both had a common ancestor, but one descendant was updated whereas the other was not).

How to reproduce

1. Place a furnace
2. Place a smoker
3. Compare bottom textures

Expected results

Consistency.

Actual results

Nopers.