So there’s this one new function in the source. The MCP name for it is EntityPlayer.func_35190_e. It’s new in 1.8. It does nothing - it returns true.
So why is it interesting?
Well, it’s now called by dye (including bonemeal), hoes, seeds, block items, and flint&steel;, before the item use function fires.
Because it’s a function of the player, the only thing it manages to accomplish is killing any non-player attempts to use those items, by throwing a NPE. And yes, that means it completely and utterly cripples the Deployer.
Nothing is ever easy.
(And yes, I fixed it. 7 new classes touched by Forge. Yowch. Still, I’m not the only one using those functions.)