@overrides(SettingsMigrator)
def migrate_from_0_to_1(self, settings):
    self.assertEqual(self._old_settings, settings)
    self._from_0_to_1_called = True
    settings[SettingsMigrator.SETTINGS_VERSION] = 1
@overrides(SettingsMigrator)
def migrate_from_0_to_1(self, settings):
    self.assertEqual(self._old_settings, settings)
    self._from_0_to_1_called = True
    settings[SettingsMigrator.SETTINGS_VERSION] = 1