The resource pack attached to MC-214686 offers a complete fix for this issue. Mojang have my full permission to (and are encouraged to) replace the affected vanilla model files with the contents of the resource pack.

The bug

Unlit redstone torches are lit the same on all sides despite not currently producing light, giving them a slight out of place feel.

How to reproduce

1. Place down 2 blocks
2. Set a redstone torch on one and a fence post on the other
3. Power the block with the torch on it with a lever
4. Compare the lighting of the torch to that of the fence post

Expected behaviour

The lighting of the torch's faces depends on the face.

Actual behaviour

All of the faces of the torch are seemingly lit the exact same.

How to fix

The resource pack attached to MC-214686 fixes this issue completely.