Read the config file and store it (when valid)

def _read_configfile(self):
        """Read the config file and store it (when valid)"""
        rc = self.config_filename
        if not os.path.isabs(rc):
            rc = os.path.join(os.path.expanduser('~'), self.config_filename)
        # If there is a setup.cfg in the package, parse it
        files = [f for f in [rc, 'setup.cfg'] if os.path.exists(f)]
        if not files:
            self.config = None
            return
        self.config = ConfigParser()
        self.config.read(files)
        if (not self.is_old_pypi_config() and
                not self.is_new_pypi_config()):
            # Safety valve
            self.config = None