When placing hay bales normally, all side textures are shown correctly.
When placing hay bales sideways, one of the four side textures is flipped upside-down (see screenshots).

To be exact:

• When "hay_block_top.png" faces in north-south direction, "hay_block_side.png" facing west is incorrectly flipped.
• When "hay_block_top.png" faces in west-east direction, "hay_block_side.png" facing north is incorrectly flipped.