Rename a file located in datadir.

        src_basename and dest_basename are the basename of the source file
        and of the destination file, respectively.

def rename(self, src_basename, dest_basename, datadir="outdir"):
        """
        Rename a file located in datadir.

        src_basename and dest_basename are the basename of the source file
        and of the destination file, respectively.
        """
        directory = {
            "indir": self.indir,
            "outdir": self.outdir,
            "tmpdir": self.tmpdir,
        }[datadir]

        src = directory.path_in(src_basename)
        dest = directory.path_in(dest_basename)

        os.rename(src, dest)