Description:
------------
Environment

I'm testing this problem on Windows 7 Ultimate x86 english.

Configuration changes little is required to reproduce.

1. Please open "Control Panel".
2. Please click "Change display language" link.
3. Please select "Administrative" tab and click "Change system locale..." 
button.
4. Please change current system locale "Japanese(Japan)".

The above procedure is not needed if you want to try in the Japanese versions of 
Windows.

php in immediately after installation, the default state is also php.ini (does 
not exist).

Problem

is_dir() will lie If you create a folder that contains the "\x5C" in the string.
It may YYYY is included in the second byte of Shift_JIS.
For example ソ(\x83\x5C).
More example: 
https://ja.wikipedia.org/wiki/Shift_JIS (japanese)


Test script:
---------------
@mkdir("a");
@mkdir("\x83\x5D");
@mkdir("\x83\x5C");

$dir = './';
if ($dh = opendir($dir)) {
    while (($file = readdir($dh)) !== false) {
        $path = $dir . $file;
        $type = filetype($path);
        $type2= is_dir($path) ? 'dir' : 'file';
        $comp = $type == $type2 ? 'OK' : 'NG';
        echo "filetype()[".str_pad($type, 4)."] == is_dir()[".str_pad($type2, 4)."] -> $comp: {$file}\n";
    }
    closedir($dh);
}


Expected result:
----------------
filetype()[dir ] == is_dir()[dir ] -> OK: .
filetype()[dir ] == is_dir()[dir ] -> OK: ..
filetype()[dir ] == is_dir()[dir ] -> OK: a
filetype()[file] == is_dir()[file] -> OK: test.php
filetype()[dir ] == is_dir()[file] -> NG: ソ
filetype()[dir ] == is_dir()[dir ] -> OK: ゾ


Actual result:
--------------
filetype()[dir ] == is_dir()[dir ] -> OK: .
filetype()[dir ] == is_dir()[dir ] -> OK: ..
filetype()[dir ] == is_dir()[dir ] -> OK: a
filetype()[file] == is_dir()[file] -> OK: test.php
filetype()[dir ] == is_dir()[dir ] -> OK: ソ
filetype()[dir ] == is_dir()[dir ] -> OK: ゾ