Can build catapults without iron working

I conquered some cities from another civ that had hooked up iron, and then I could build catapults without having researched iron working. I don't think this is the intended behaviour. I can provide a save file if needed.

Saves are always needed when reporting bugs.

did you have iron via trading with someone? If not, when you look at your resources page, or what you can trade to AIs, does it show you do have iron available, even though you can't see it on the map?

I had no iron trades. Iron is not shown in the top bar or in the trade bartering window.

I attached a save file.

EDIT: The iron is on that plains tile to the south of Osininka.

I can indeed confirm it in his save (Digital Deluxe, worked with 1.0.0.17). I built a catapult and it then showed 0 iron in the top bar, but nothing in the tooltip. I could not build a second catapult. The catapult did not have a negative modifier from a missing resource. The iron most likely comes from the mine on the plains tile, so the bug seems to have given you 1 iron only despite you not having researched ironworking. Quite mysterious.

I can third this, but unfortunately don't have the save. I only had the three cities I'd built, no puppets, and no resource trades (except a gift of silver to Askia). Teched Mathematics but not even Bronze Working, and could build Catapults. Once I built one, it showed 5 iron in the top bar, but no tooltip. Found out later that I had settled on a 6-patch of iron.