The A/B test does not have any impact on the search engine optimization. Indeed, indexing bots (Google, Yahoo!, Bing, etc.) are automatically excluded from the A/B tests. They can only see the original page of your website, so it does not affect your SEO nor the results of your A/B test.
<meta name="robots" content="noindex">
For further information about this tag, please refer to Google support and the article Block search indexing with meta tags.