the removed comment means, if we tell server we support utf8 and server return utf8, then no need to convert, so the convert could be conditional.
while we now have no way to tell server that, but the server did use utf8 at most time, but we send back to server with non-utf8 currently, that's what this pr fixed. and no matter what server returned, we both need convert it to utf8 because we use utf8 to save filename/path, then we can compare the converted one with the server returned one, so we can tell whether the server returned to us is not utf8, so I comment convert to utf8 anyway. the main comment moved to above of the line 'url.SetProtocolOption("utf8", "0");', by compare we detected the filename/path is non-utf8, and we tag it with protocol option, and in CurlFile to send back to server with same encoding, that's how this pr works with both utf8 and non-utf8 server returned filename/path.