'Update defaults after a change in version'

def _update_defaults(self, defaults, old_version, verbose=False):

    old_defaults = self._load_old_defaults(old_version)
    for (section, options) in defaults:
        for option in options:
            new_value = options[option]
            try:
                old_value = old_defaults.get(section, option)
            except (cp.NoSectionError, cp.NoOptionError):
                old_value = None
            if ((old_value is None) or (to_text_string(new_value) != old_value)):
                self._set(section, option, new_value, verbose)
