“ Whether or not that hearing was adequate need not, however, be determined, for we are satisfied from the record, which includes the trial transcript, that in any event this was a case where no hearing was required under the statute, because 'the files and records of the case conclusively show' that the petitioner was entitled to no relief. Therefore, and necessarily without approving or disapproving the view of the Court of Appeals on what now appears an extraneous issue, 108 U.S.App.D.C. 375, 282 F.2d 858, we dismiss the writ as improvidently granted. It is so ordered. ”