Furnace Factory Blocks work regardless of bus input

[Aeraggo]

It seems a Factory Block will produce even if the bus isn't receiving the right resource from a resource patch.

Steps to reproduce:
Create a Resource Patch with any material (Iron Ore, in the case where I encountered this issue)
Create a Bus to transport the resources
Create a Factory Block with any furnace recipe (even one different from the input)
Prep a space and add a furnace
The Factory Block appears to work regardless of input