Not a bug reCAPCTHA has old incorrect URL in library/Zend/Service/ReCaptcha.php

[Mouth]

Looks like http://api-verify.recaptcha.net is no longer being handled, and instead redirected.
Proper URL is https://www.google.com/recaptcha/api/verify

captcha_recaptcha template has correct url for noscript iframe src

 

[Chris D]

Indeed the base URL redirects, but then again that's not actually the URL which is used and it may have always been like that.

The URL which is used still works fine and doesn't redirect:
http://api-verify.recaptcha.net/verify

 

[Mouth]

https://developers.google.com/recaptcha/docs/verify

 

[Mike]

I have confirmed that the API URL still works. Note that what you're referring to is a different version of the API (it's NoCAPTCHA) which has different requirements.