如何修复“复数形式可能是危险的”django错误？

I don't get it. If I set the Accept-Language header to anything other than "en" (de, pl, es) or even something that doesn't exist (like xxs), the app doesn't spit out this error, but it does when I set it to "en". It happens only on windows (newest gettext tools). Here's the stack trace: he