Divinity:Original Sin Patch v1.0.72
-The seller of secrets now only has 1 ability book and 1 stat book instead of regenerating those
It is a bug, because the developers meant to change it yet failed to actually do so.
It's unclear whether or not it is an exploit, glitch, or cheat.
For what it's worth, I'm glad it didn't actually change. I don't agree with the decision to remove regeneration from the books.