Add python-version specific environment variable

Environments
1

I am still struggling with the basics of TravisCI. There really should be a GUI or frontend that prevents users from writing corrupt configs.

language: python
os: linux
dist: focal

arch:
 - amd64
 - ppc64le

env:
  PYTHONUNBUFFERED=1

python:
  - "3.8"
  - "3.9"
  - "3.11"

jobs:
  include:
    - python: "3.8"
      env: SYSTEM_SITE_PACKAGES=true

3 Python versions x 2 architectures should result in 6 jobs. But it don’t. There are more jobs.
Becuase Python 3.8 runs multiple times once with “SYSTEM_SITE_PACKAGES” and once with “PYTONUNBUFFERED”.

But I want both variables in on job together. I defined PYTHONUNBUFFERED globally. And SYSTEM_SITE_PACKAGES should be added to env just for Python 3.8. Logical to me but seems not for Travis.

EDIT: I assume that TravisCI use a paradigm that is very different from the one do have in my mind. I really try to understand. I just want Travis to mix “arch” and “python” in all combinations and then add(!) to this implicit configuration some extras (e.g. the “env” element for Python “3.8” on both(!) architectures).