Hitting hostile enderman makes them neutral

Hitting hostile enderman makes them neutral, thus an easy kill, regardless of difficulty.

Steps to Reproduce:
1. Find an enderman
2. Look into the eyes to make him hostile
3. Use any sword or hand to hit enderman
4. Now enderman should become neutral

Sometimes the same happens for zombies or skeletons (neutral for 1-5 seconds, works by hitting with diamond sword).