Description:
------------
Using Windows 7, create a directory "C:\dirtest\Au". Run the test script. Output produced is: 

bool(true)
bool(true)
bool(false)
bool(false)
bool(false)
bool(false)

although neither $file1 nor $file2 exist! Expected output would be "bool(false)" in all cases.

Test script:
---------------
<?php
$file1 = 'C:\dirtest\Au\aux.gtb';
$file2 = 'C:\dirtest\Au\bux.gtb';

var_dump(is_file($file1));
var_dump(file_exists($file1));
var_dump(is_readable($file1));

var_dump(is_file($file2));
var_dump(file_exists($file2));
var_dump(is_readable($file2));

Expected result:
----------------
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)

Actual result:
--------------
bool(true)
bool(true)
bool(false)
bool(false)
bool(false)
bool(false)