portmgr@ plans to make python 3.6 default version of python in the next days. cad/freecad fails to build with DEFAULT_VERSIONS=python=3.x Failure log: http://package18.nyi.freebsd.org/data/112amd64-default-PR234633/2019-02-18_09h32m09s/logs/errors/FreeCAD-0.17.13541_6.log
I'm not sure FreeCAD 0.17 will even work with Python 3 (IIRC full Python 3 support was on the roadmap for 0.18). If it's urgent, feel free to restrict FreeCAD to Python 2 - I cannot look into this before end of the week.
A commit references this bug: Author: antoine Date: Mon Feb 18 17:12:36 UTC 2019 New revision: 493279 URL: https://svnweb.freebsd.org/changeset/ports/493279 Log: Fix build with DEFAULT_VERSIONS=python=3.x PR: 235835 Changes: head/cad/freecad/Makefile