Incorrect Piston Shading

The Bug

When placing an energy source next to a piston in mid-air, certain placements will result in an incorrect shading on the top of the extended part of the piston.

How To Reproduce

Place an energy source next to a suspended piston that is facing a cardinal direction.

Notes

This only occurs when a piston is suspended in air.

This occurs with both piston types and all redstone energy sources.

When the energy source is placed directly east or west of the piston the shading is normal.