Just received an email stating with pre-orders of Fractured but Whole for PC and PS4 you'll receive a digital code for Stick of Truth.
Looks like this may be limited to preorders made through the ubisoft store (linked to deal) though I'm not 100% on that.
No mention of Xbox one..
Taken from ubisofts site:
- Towelie: Your Gaming Bud
- Free digital copy of The Stick of Truth (available now for PC Download, and at game release for PC DVD, PS4, Xbox One.)