fix #1658 scikit-learn==0.20 for python 2.7
fix #1658 scikit-learn==0.20 for python 2.7

mrakitin/sirepo,radiasoft/sirepo,mkeilman/sirepo,radiasoft/sirepo,mkeilman/sirepo,radiasoft/sirepo,mrakitin/sirepo,mkeilman/sirepo,mrakitin/sirepo,radiasoft/sirepo,mrakitin/sirepo,mkeilman/sirepo,radiasoft/sirepo