The abrupt resignation of Nigeria’s top petroleum regulator shortly after the launch of one of the country’s largest oil block auctions in years has sparked fresh concerns. Gbenga Komolage, head of the Nigerian Upstream Petroleum Regulatory Authority, and Farouk Ahmed, head of the Nigerian Midstream and Downstream Petroleum Regulatory Authority, have both resigned. Their exits came after Aliko Dangote, Africa’s richest man and the owner of the giant Dangote Refinery, criticized Ahmed for allowing cut-price fuel imports that threaten…