I have Odoo v12 Community on-premise (Windows) that I would like to upgrade to v17 and start using a bit more.

I attempted database upgrade as per https://www.odoo.com/documentation/17.0/administration/upgrade.html

Problem: 

python <(curl -s https://upgrade.odoo.com/upgrade) test -d -t 17

executed from Odoo\python directory returns "The system cannot find the file specified."

python <(curl -s https://upgrade.odoo.com/upgrade) --help

returns "The filename, directory name, or volume label syntax is incorrect."

I tried installing fresh Odoo 17 on a different host, importing the database and running update from there, and got the same result.

Both hosts are Windows servers, and both only have Python that was installed with Odoo. Odoo itself works. 

Any suggestions what am I doing wrong?