The bug
When a mansion generates over trees, the foundation of the mansion will be stopped by the trees.
How to reproduce
Use the seed 8 on a "dark forest hills" buffet world, and teleport to 5875 80 5456. Nearby you will see that the tree will interrupt the mansion foundation.
Attachments
Comments 2
Can confirm in 21w16a.
Now it affects the trees next to the entrance, but somehow the ones in the given location don't interrupt the foundation anymore.
Edit: can this issue be renamed into "Mansion foundations are interrupted by vegetation", so that it can also include grass and other non-solid plants? (see image above)
gaspoweredpick
Partially fixed so that the trees don't generate under the mansion now. They still will interrupt the foundation, but only if the trees end up too close to the mansion. I also updated the screenshots accordingly.