How to handle "Double requirement given" error when installing requirements for Odoo

Question

I'm trying to get started with Python and Odoo. According to the instructions , I'm supposed to execute pip install -r .\\requirements.txt , upon which I get an error.

Ignoring gevent: markers 'sys_platform != "win32" and python_version < "3.7"' don't match your environment
ERROR: Double requirement given: gevent==1.4.0 (from -r .\\requirements.txt (line 9)) (already in gevent==1.5.0 (from -r .\\requirements.txt (line 8)), name='gevent')

I do understand that the following lines are the issue, the first being omitted due to unsatisfied condition, the latter two colliding. I run Python 3.8.5 and pip 20.2.3 under Windows 10, so those conditions are fullfilled.

gevent==1.1.2 ; sys_platform != 'win32' and python_version < '3.7'
gevent==1.5.0 ; python_version >= '3.7'
gevent==1.4.0 ; sys_platform == 'win32'

Being a total noob in the area, I can't even tell if it's a Python or an Odoo issue, let alone, how to trouble-shoot it. I've tried removing the lines individually, which allowed to pass that part of the installation. However, as expected, it led to some errors further on, which I don't even quote as I'm sure I'm not supposed to horse around in the default requirements.py file provided by people way smarter than me.

Googling didn't get me far for those specific packages, while general discussion (regarding other packages) was aligned with the conclusion that they just won't work together. Didn't made me much wiser, which likely depends on my incompetence from the area.

How can I approach the issue? And/or - what keywords are of significance when googling it further?

Answer 1

https://www.odoo.com/documentation/13.0/setup/install.html

Odoo provides packaged installers for Windows

Answer 2

I faced same issue. First I remove the line

gevent==1.4.0 ; sys_platform == 'win32'

and could proceed, but few steps later I had to learn that Odoo is not ready for Python 3.8. You get issues with Pillow ...

Installing Python 3.6 solves the problem.