If you are using Docker to build TinkerPop, please note that I had to bump the Python version from 3.5.3 to 3.6.9 as the build was failing on the former. 3.5.3 seems to be EOL and something in that python stack decided it wasn't going to support that version anymore. 3.6.9 has always been fine on my system and seemed to be good to go for docker on builds of 3.4-dev and master.
As a result, you will want to delete your docker images and rebuild them with the latest changes.
