Support for unlink().
The file will not be deleted from the stream as this is a read-only stream wrapper.
string $uri: A string containing the uri to the resource to delete.
bool TRUE so that file_delete() will remove db reference to file. File is not actually deleted.
Overrides LocalStream::unlink
http://php.net/manual/en/streamwrapper.unlink.php
public function unlink($uri) {
trigger_error('unlink() not supported for read-only stream wrappers', E_USER_WARNING);
return TRUE;
}