[speedplane]

> So Ubuntu is open-source, but if I fork it, it comes with « Ubuntu » in package names, therefore I’m infringing on their trademark?

Yup. However, I suspect that Ubuntu gives a pretty permissive trademark license in their distribution.

This isn't a theoretical argument, the Android OS is open source, but the "Android" brand is a protected trademark. If you're a cell phone manufacturer, you can use the Android code freely, but if you want to put an Android sticker on your phone, you have to follow Google's rules.