public function findVersionOfFile($file, $version)
    {
        if($file == null || ($f2 = $this->findOriginalFileToVersion($file)) == null ||
            $file->getAbsoluteFilePath() != $f2->getAbsoluteFilePath()){
            return null;
        }
        $name = $this->versionFileName($file, $version);
        $f = new FileImpl($file->getParentFolder()->getAbsolutePath()."/".$name);
        return $this->containsFile($f)?$f:null;
    }