Duplicate headers received from server

I'm trying a fresh install of the latest D8 code (36975492e9222753eba723cd5e07da1de1bb9ab1) and I know this is far from finished, but it seems the installer is throwing me a weird error. After installing the modules, and finishing all ajax requests, the final request to

I'm running this with nginx 1.4.1 and PHP 5.4.4. I'm going to dive into the code to try and find where this comes from. Maybe somebody already had this error before...? Nothing in the error logs either.

It seems however that the install functionality itself is not affected by it and the Drupal site is setup correctly.

Edit: more specificly "Multiple Location headers" seem to be received by the request, that's why Chrome throws me an error.