Steps to Reproduce:

1. Enchant a sword with Fire Aspect 2 and Looting 3
2. Spawn a chicken
3. Type /effect @e[type=chicken] resistance 30 2 in the chat
4. Hit the chicken once with the sword
5. Wait for the chicken to burn to death
6. Repeat steps 2-5 multiple times

Observed Results:
The chicken always drops 1 cooked chicken.

Expected Results:
The chicken should drop 1-4 cooked chicken.

Original Description:
If you put looting 3 on your sword while also having fire aspect, mobs will not be effected by the looting 3. The mob has to die from the fire aspect itself and not from a final blow from a sword. Doesn't matter if you hold out your lootin 3 fire aspect 2 sword out the whole time or not. If you use a looting sword without fire aspect its a stark difference between having and not having fire aspect on it. Again it has to die from burning up by the fire aspect and not a final swing from the sword.