Survival spawner bug

Your username: xGapples might be changing to something else soon
In which minigame/server does the bug occur: Survival
Detailed description of bug: So basically in survival people use mobspawners either buy in game from a player/auction/or buy from the store.. make farms with them, 1 certain farm has broken for me i dont know if its anyone else or just me. but my wither skeleton farm seems to be broken and only spawns skeletons instead of wither skeletons it used to work like this spawner in the nether set to skeleton = wither skeleton spawns and now its just skeleton so i dont know if its the plugin or the server but im reporting it thanks for reading -Gapples

 

They turned this off so it isn't as OP.
http://itsjerryandharry.com/threads/factions-wither-glitch.66423/