Please help me understand what's happening here.
To create my custom furnace I copy and pasted the prototype data for the steel furnace and modified it.
Here's my code:
https://github.com/TheHorscht/ChokeOnSm ... urnace.lua
But I noticed a bug where the smoke was sometimes coming from the wrong position, turns out it's because the entity is rotatable.
So I needed to add the "not-rotatable" flag to my custom furnace and now it works as it should (hopefully).
My question now is, why is the original steel furnace not rotatable even though it doesn't have the "not-rotatable" flag (see here, warning big file)? Why did I have to add it to my own prototype?