python3-sklearn and python3-sklearn-lib are in unstable now, so this is pretty much fixed.
The python 3 packages currently recommend some python 2 packages, I have a commit here [1] that fixes it, but it has not been merged and released yet. 1: https://github.com/cbaines/scikit-learn/commit/8aa3acc700e2a899f5ffdf93464fcfe4089b230b
