Make a directory called targetpath.

def makedir(self, tarinfo, targetpath):
        """Make a directory called targetpath.
        """
        try:
            # Use a safe mode for the directory, the real mode is set
            # later in _extract_member().
            os.mkdir(targetpath, 0o700)
        except EnvironmentError as e:
            if e.errno != errno.EEXIST:
                raise