What happened to custom spritesheets?

Supposedly, IC 1.70 added the ability for CropCards to specify their spritesheet. As far as I can tell, however, this capability doesn't actually exist in 1.71. There's no mention of it in the CropCard API, and if I drill down to the underlying BlockCrop and TileEntityCrop classes, I don't see them doing anything that would allow it. Where did it go?

... now how the heck did I miss seeing that before? facepalm

I'd delete the thread, but I suspect I'm not the only one who's not terribly observant. So I'll leave my shame to educate others.