Yep, the smaller rotation direction is used.
I should have been more clear in my answer.
When the Spine Runtimes mix (interpolate) world rotations from different poses (eg AnimationState tracks) then my answer is correct: the smaller rotation direction (at the start of the mixing) is used. This is what I was thinking of, but now I see it probably wasn't what you were asking.
To interpolate between two keys in a rotate timeline, before 4.0 my answer is also correct: you would rotate in the smaller direction. However in 4.0+ you just interpolate between the key values without caring about which way around is shortest. The rotation direction that results depends on the values used. Smaller to larger goes one way, larger to smaller goes the other.
