CFOTO | Future Publishing | Getty ImagesNoted short seller Hindenburg Research disclosed a bet against Carvana on Thursday, claiming the online used-car retailer's recent turnaround is a "mirage" that is being propped up by unstable loans and accounting manipulation.The report centers on Carvana's practice of loan sales as well as the business relationship between CEO Ernie Garcia III and his father, Ernest Garcia II, who is Carvana's largest shareholder.Shares of Carvana were down about 3% Thur...