We currently mandate that DM software must work with python 3.5 and above and that science pipelines must also support python 2.7. After v14 is released I would like to shift the DM baseline for python3 to be v3.6.
My motivation for doing this is so that we can agree on a minimum version when integration testing ramps up in 2018 and there is little point running tests on a version of python that we have no intention of using in production (whereas aux telescope will be arriving next year). Given that science pipelines still has to support py2.7, this won't have any visible effect on developers other than the python package insisting that 3.6 is available. Many developers are already running 3.6 but Jenkins is not testing it.