Update default python version

[gronke]

addresses #750

• Update default Python version to 3.7
• Document installation from Makefile for other Python versions in README

[igalic]

🙋‍♀️

[igalic]

given that we already have LATEST_PYTHON_VERSION we can use this directly here

[igalic]

this should still have a fallback, since we use this makefile on Travis, too.

[gronke]

It is a bit complicated. There are multiple layers of overrides happening here.

PYTHON_VERSION ?= $(TRAVIS_PYTHON_VERSION)
SELECTED_PYTHON_VERSION != if [ "$(PYTHON_VERSION)" != "" ]; then echo $(PYTHON_VERSION); else pkg info -g 'python3*' | cut -d'-' -f1 | sed 's/^python//' | sort -n | tail -n1 | sed -r 's/^([0-9])([0-9]+)/\1.\2/'; fi
PYTHON ?= python${SELECTED_PYTHON_VERSION}
pyver= ${PYTHON:S/^python//:S/.//:C/\([0-9]+\)/\1/}

1.) When no PYTHON_VERSION was set, use TRAVIS_PYTHON_VERSION
2.) If neither was set, guess SELECTED_PYTHON_VERSION using pkg info
3.) This all can be overwritten via PYTHON.
4.) Read numeric pyver of whatever version was selected

[igalic]

lies and half truths.

[igalic]

this is not entirely true…
https://www.freshports.org/devel/py-libioc it just… still doesn't have all the right dependencies…

[gronke]

Well, let's tackle this at a different time. Would you open an Issue as a reminder? 💜

[igalic]

approving this despite the failing vnet tests
We can tackle these separately