Had me all excited for a moment, but no, I don't think so. This was much bigger - think watermelon size and it definitely hung down rather than being attached to the branch. The tree is in Western Uganda if that helps. There is cacao in Uganda, but I'm pretty sure this is not it.
I think this is Telfairia pedata, oysternut. See Telfairia pedata (Sm. ex Sims) Hook. (CUCURBITACEAE) and Telfairia pedata - Useful Tropical Plants It is a vine - I think your photos show two different types of leaves. The oysternut vine is being supported by some other poor tree. :)
That's it!! Thank you. Not at all what I was thinking, but definitely correct. I'm wondering if the villager gave me the wrong name for it as I can remember thinking "oh, that's what that looks like" of a much more common nut :-)