Comment 1 for bug 1317012

I have to correct something:

It seems older Firefox versions had the same problem, but it wasn't obvious, because the default accept_languages of the firefox-locale-de package were already "de-de,de,en-us,en". In Firefox 28 the default was changed to "de,en-us,en".

Nevertheless the problem is still, that Firefox reads the setting from syspref.js and displays this correctly in about:config, but doesn't use this value when constructing the HTTP header. The problem seems to be this test: http://mxr.mozilla.org/mozilla-central/source/modules/libpref/src/nsPrefBranch.cpp#232

So the accept_languages will only be used, when they are set by a user pref, or a locked pref, but not with a "simple" pref in syspref.js.