Export issues to Excel/Word format with non-ASCII filter name does not handle the file name properly

Steps to reproduce:

1. Create a filter with the name of Russian language (e.g. тестирования фильтром)
2. Export the issues into Excel/Word format

In FireFox, the file name displayed contains the ...%B5%D0....xls. In IE, the file name can be displayed correctly.

I have also tried to attach a file with Russian name to an issue, and then download it. The file name does display correctly in both FireFox and IE.