Confluence language detection ignores weights in accept-language header

The spec for the Accept-Language header says we have a 2-3 char language string e.g. "en", optionally followed by a dash and a variant "-US", optionally followed by a quality value (weight) ";q=0.9". It just so happens to be that most if not all browsers send the highest weighted one first and then the rest in reducing order, but they don't have to do that. So a browser could in theory send "en;q=0.3,de-CH;q=0.9" and we would take it to mean they prefer English, but the spec says they prefer Swiss German 🙁