I'm not sure if this is related to the latest changes in volume rendering, I just updated my YT to see if the strange behavior of transfer function was fixed, but my old script which rotates the cube using cam.rotation now rotates the cube in strange ways, like the north vector is being redefined half way through the rotation.

Here's the script I used, and I just updated to the latest YT

(dev-yt)4-c-ce-e0-97-1e:yt-hg gso$ hg summary
parent: 6186:2ff4b9960158 tip