Hi, I think this might not be a bug, it might be a feature. But it's not mentioned in news.txt, so I wasn't sure if it's intentional or not. When a stone axe haft breaks, you don't get a sharpened stone axe head, you get a regular stone, which cannot be rehafted.
This makes sense to me because maybe the stone head is also no longer sharp after all these trees I've chopped with it.
Worn haft of your stone-axe breaks!
The stone drops on the ground.
[...]
Huh? It's not possible to haft stones!