Clint Reilly, the wealthy real estate developer who sued unsuccessfully to stop the sale of the Chronicle six years ago, plans to file a federal lawsuit tomorrow (July 14) to stop the sale of the Mercury News, Contra Costa Times and other former Knight Ridder papers in Northern California to Dean Singleton’s MediaNews Group, the Associated Press is reporting tonight. His argument is that the Chronicle and the Merc will no longer be competitors if the $1 billion deal goes through because Chronicle owner Hearst Corp. is contributing $263 million to the deal. Reilly is seeking an injunction in federal court to stop the sale. On June 28, Singleton said the sale would close in four weeks, but an exact date hasn’t been announced. [BusinessWeek columnist Jon Fein says MediaNews and Hearst are teaming up with Yahoo on a new project]