Changing difficulty bug (Mobs)

1. Set difficulty to "easy"
2. Set time to "night"
3. Wait some seconds
4. Change difficulty to "peaceful"
5. Perform the command:

/testfor @e

The chat will show you monster names

!You can even use:

/tp @p @e[type=Spider,c=1]

[23:01:58 INFO]: Client> [23:01:58] [Server thread/INFO]: Changing difficulty to PEACEFUL, from EASY
[23:03:07 INFO]: Client> [23:03:07] [Client thread/INFO]: [CHAT] '{Motion:[0.0,0.0,0.0],direction:[0.0,0.0,0.0],UUID:1-1-1-1-1}' ist keine gültige Zahl
[23:03:14 INFO]: Client> [23:03:14] [Server thread/INFO]: [Marcono1234: Objekt erfolgreich erzeugt]
[23:03:14 INFO]: Client> [23:03:14] [Client thread/INFO]: [CHAT] Objekt erfolgreich erzeugt
[23:03:25 INFO]: Client> [23:03:25] [Server thread/INFO]: [Marcono1234: Marcono1234 wurde zu entity.WitherSkull.name teleportiert]
[23:03:25 INFO]: Client> [23:03:25] [Client thread/INFO]: [CHAT] Marcono1234 wurde zu entity.WitherSkull.name teleportiert
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Marcono1234]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found entity.WitherSkull.name]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Zombie]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Spinne]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Hexe]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Spinne]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Creeper]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Zombie]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Zombie]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Zombie]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Spinne]
[23:03:37 INFO]: Client> [23:03:37] [Server thread/INFO]: [Marcono1234: Found Spinne]
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Marcono1234
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found entity.WitherSkull.name
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Zombie
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Spinne
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Hexe
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Spinne
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] That entity cannot be found
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] That entity cannot be found
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Creeper
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Zombie
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Zombie
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] That entity cannot be found
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] That entity cannot be found
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Zombie
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Spinne
[23:03:37 INFO]: Client> [23:03:37] [Client thread/INFO]: [CHAT] Found Spinne