After https://github.com/freeipa/freeipa/pull/8324 bad referrer for sync_otp ends with 400, this is a change from old behavior. Since the endpoint is used through ipa command ipa otptoken_sync. We should revert the change for otp token implemented and simply not check the referrer as we did in the past. We could also add referer to the request, but referer is commonly used by browsers, elsewhere not so much.

The to be deleted block:

        if not self.check_referer(environ):
            return self.bad_request(environ, start_response, 'denied')