Description:
------------
Trying to check if a file to include exists. Path, where file to be checked, is in open_base_dir. But if the file does not exists, the function throws a warning concerning open_basedir restrictions

Reproduce code:
---------------
if (file_exists('/opt/cms/modules/stats/frontend/stats.parser.html.class.php')) {
  echo 'found';
}

Expected result:
----------------
file_exists() returns false without a warning

Actual result:
--------------
Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(/opt/cms/modules/stats/frontend/stats.parser.html.class.php) is not within the allowed path(s): (/srv/www/htdocs/web2:/usr/lib/php:/opt/cms