The production menu was used for showing information. Now the sawmill is no producer anymore and thus has no production menu. Instead, the sawmill adds the hint manually now.
The sawmill splits up objects on Collection(). That means you could put trees into the sawmill and even without power could you then take out the wood (that was yet to be ejected).
This is solved by this commit as you cannot take objects out of the sawmill manually anymore. The sawmill still displays the wood that is to be produced (because I found that cool).