Encoding in file included by geo

Hi,

I use geo module in nginx 1.8.1. It has several geo directives that include files with IP to geodata mappings.

Unfortunately, the encoding in city and country names is messed up when the variables are sent back as HTTP headers or passed to the backend. The included files are in UTF-8 without BOM.

So, the question is: in what charset should I encode the files that are included by geo directives?