OMAHA, Neb. (AP) — Warren Buffett’s company is abandoning its purchase of a natural gas pipeline from Dominion Energy because of uncertainty about whether the deal could get regulatory approval. Berkshire Hathaway Inc. will receive a $1.3 billion refund on the proposed purchase of Questar Pipelines that was also supposed to include $430 million of Dominion’s debt when it was announced a year ago. The Richmond, Virginia-based energy company said it still plans to sell Questar and will work to find another buyer by the end of the year. Dominion also said the decision won’t affect its financial outlook.