Comment 1 for bug 159146

This may relate to several EN variants set in the user's browser.

    HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.9,de-CH;q=0.8,de;q=0.6,de-DE;q=0.5,en-GB;q=0.4,en-us;q=0.3,en;q=0.1

en-US, en-us, and en are all EN in Launchpad.

utilities.geoip.RequestPreferredLanguages should use a set() instead of a list()
to ensure each language that is looked up by code is unique.

I'm setting this to confirmed because I think we can easily write a test to confirm this OOPS.