Breaking a [trade] sign of items like bread, tools, saddles, etc. (Non-stackables) used to stack them. I think this is a bug, and it was fixed.

This was actually a useful bug, and being able to stack my 6.5 chests worth of bread would be helpful :p Being able to stack tools would make mining more efficient, and stacked signs would bring ease to major shop owners, or Mayors.

In summary: Sign stacking was patched, I'm suggesting that it be unpatched :p