The Bug:

Dispensers are able to place carved pumpkins to create snow golems and iron golems as well as place wither skeleton skulls to create withers. However, if a block such as grass, snow layer or fire is in front of the dispenser, it is unable to place the block even though the player can. It can only place these blocks if the block in front of the dispenser is air. These blocks do not affect the placement of shulker boxes.

Steps to Reproduce:

1. Build the configuration as seen in MC-217270.png.
2. Place a carved pumpkin inside the dispenser.
3. Attempt to power the dispenser.
   The pumpkin is not placed due to the snow layer.
4. Break the snow layer.
5. Attempt to power the dispenser.
   The pumpkin is placed and an iron golem spawns.