File.expand_path(File.dirname(__FILE__)) return wrong encoded result
A test.rb in a nonascii path with the follow content:
Run it with utf-8 as internal encoding.
expect result: UTF-8
Tested on windows 7.
I submited a patch to fix this problem but in a wrong way, check it(https://bugs.ruby-lang.org/issues/8774), hope it can help to fix this problem.