Alloy smelter only smelts 7.9-ish items from one piece of coal

[mystise]

Issue Description:

Smelting items in the alloy furnace with coal only processes 7 full items, and doesn't complete the 8th. It never burns more coal until you place in more processable items, and thus the 8th item will never complete without adding a 9th or further item.

How to reproduce:

Place stack of coal in fuel slot
Place enough items for 8 recipe runs in input slots (for example, 8xSand -> 8xGlass)
Only 7 glass are produced, the 8th sand is consumed but the progress stops short of producing the 8th glass
Place another sand in the input, and the 8th glass will output almost immediately

Affected Versions (Do not use "latest"):

• Teckle: 0.6.470
• Forge: 14.23.5.2768
• Minecraft: 1.12.2