I tried to install some ad-ons, and they require dependencies that now aren't normally available or even buildable in a py35 flavor, ex. py-requests. Now python ports need USE_PYTHON=allflavors to enable all flavors, otherwise only py27 and py36 are available. Additionally, it needs USES=fortran, because some add-ons require py-numpy, which in turn doesn't run when the package is built w/out USES=fortran (I think). I particularly tried this add-on: https://github.com/nortikin/sverchok Thanks! Yuri
https://reviews.freebsd.org/D13721