GeezerVison

Fix issue #2909

I haven't included a test case with this fix because

1. unicode issue is better to be judged by eye.
2. this issue only repros in a non-english windows system with ps running under cmd window. Our current test environment won't touch this scenario.

Thus, one time manual verification might be enough.

Summary of the issue:

Under non-english OS, if user start ps core under comandline and type "help ", the output will be one character per line

Root cause of the issue:
Only Nano needs to use Unicode, but Windows and Linux need the default encoding. The way we judge if the current os is Nano server has been outdated.
Fix:
Update the condition we use to judge nano server.