Craft\Import_HistoryService::version PHP Method

    public function version($history, $entry)
    {
        // Get previous version
        $entryRevisions = craft()->entryRevisions->getVersionsByEntryId($entry, false, 2);
        $version = end($entryRevisions);
        // Save
        $log = $this->getNewImportEntriesRecord();
        $log->historyId = $history;
        $log->entryId = $entry;
        $log->versionId = $version ? $version->versionId : null;
        $log->save(false);
    }