When I remove enctype="multipart/form-data" from the form in registerComplete.tpl it works. So this has to do with encryption and maybe that I don't have HTTPS on my local machine. So then my question is, why is this not on the form that transmits the username and password?
I doubt this has been explored at all, since this being a forum software in general and not something like Google Docs or any other collaborative software out there in the wild. I would like to see it as something Discourse has with there "Wiki Posts" but I won't suspect it to be even a low priority for the devs.