Странное поведение is_dir - Коммерческие вопросы

echo JPATH_SITE.DS.$_temp  
echo (int) is_dir(JPATH_SITE.DS.$_temp);
echo (int) is_dir('/home/gccsdorg/public_html/images/mp3');

/home/gccsdorg/public_html/images/mp301

string(1) "/" 

$path = JPATH_SITE.DS.$_temp;
echo (int) is_dir($path);

is_dir((A.$b.'c'))

/home/gccsdorg/public_html/images/mp301

/home/gccsdorg/public_html/images/mp3

vardump(((JPATH_SITE.DS.$_temp)==='/home/gccsdorg/public_html/images/mp3'))

DS

/**
 * A Folder handling class
 *
 * @since  11.1
 */
abstract class JFolder
{
.......
        /**
	 * Wrapper for the standard file_exists function
	 *
	 * @param   string  $path  Folder name relative to installation dir
	 *
	 * @return  boolean  True if path is a folder
	 *
	 * @since   11.1
	 */
	public static function exists($path)
	{
		$pathObject = new JFilesystemWrapperPath;

		return is_dir($pathObject->clean($path));
	}
}