mbi/django-simple-captcha — pull request #70 by joshuajonah (2014-08-28 14:51:09+00:00)
Title: Changed missing captcha url to respond with an HTTP 410 Gone status to a...

...void crawlers indexing these urls when they expire.

I was getting a ton of "Missing URL" errors in Google Webmaster Tools as it was indexing all the expired captcha store urls. This will cause it to ignore old ones.