MinecraftForge/FML — pull request #553 by MattsMc (2014-10-31 15:26:22+00:00)
Title: Fixed MOD HAS DIRECT REFERENCE System.exit() THIS IS NOT ALLOWED REROUTING TO FML!

[main/WARN] [FML]: MOD HAS DIRECT REFERENCE System.exit() THIS IS NOT ALLOWED REROUTING TO FML!
[FML]: Offendor: net/minecraft/server/gui/MinecraftServerGui$1.windowClosing(Ljava/awt/event/WindowEvent;)V
[main/WARN] [FML]: Use FMLCommonHandler.exitJava instead

You guys may have to play around with the line that the patch is getting applied to, i'm not completely shure about it.