I guess i got the idea it was working from the following blog post:
http://build.prestashop.com/news/prestashop-1703-maintenance-release/
"Want to upgrade using the 1-Click Upgrade module? Make sure to upgrade the module itself first! This way you will have access to a new, 1.7-specific channel, which makes upgrading safer for merchants. Upgrading from 1.7.0.0 to 1.7.0.3 should be smooth as silk -- but do a safety backup anyway :)"