If you put a head in a dispenser and try to dispense it, it fails(as it's supposed to unless making golems), but it makes the particles for dispensing anyway.
What I expected to happen was: Nothing
What actually happened: It made particles.
Steps to reproduce
1. place a dispenser and put a head in it
2. activate the dispenser
3. look at the particles coming out of it.
The dispenser is showing that it's being ticket, but cannot dispense anything since the appropriate target is not there.