Fix CaptchaProtectedResourceTests.test_render_GET_noCaptcha unittest.
Fix CaptchaProtectedResourceTests.test_render_GET_noCaptcha unittest.

We shouldn't return ``(None, None)`` in a stub method when all the other
methods and child classes expect ``(str, str)``.

mmaker/bridgedb,wfn/bridgedb,pagea/bridgedb,mmaker/bridgedb,pagea/bridgedb,wfn/bridgedb