Snow Golems, Iron Golems and the Wither can be created horizontally or upside down

The bug

Snow Golems, Iron Golems and the Wither can be created horizontally or upside down (but this only works if the pumpkin / heads are placed last).

Examples

Here are a few examples:

• Snow Golems: Snow Golem can be created horizontally or upside down.mp4
• Iron Golems: Iron Golem can be created horizontally or upside down.mp4