Bing has a list of regions that it supports and some of these regions may have more than one possible language. In some cases, like Switzerland, these languages are always shown as options, so there is no issue. But in other cases, like Andorra, Bing will only show one language at the time, either the region's default or the request's language if the latter is supported by that region. For example, if the HTTP request is in French, Andorra will appear as fr-AD but if the same page is requested in any other language Andorra will appear as ca-AD. This is specially a problem when Bing assumes that the request is in English because it overrides enough language codes to make several major languages like Arabic dissappear from the languages.py file. To avoid that issue, I set the Accept-Language header to a language that's only supported in one region to hopefully avoid these overrides.