URLs with action=render are indexed by external search engines like Google. For example, see https://www.google.com/search?q=site:en.wikipedia.org+inurl:action%3Drender .
I'm not sure the best approach to fix this. The pages are not well-formed (there's no <head> at all), so I don't know whether a <meta> robots directive (http://www.robotstxt.org/meta.html) will work. It might be necessary to use robots.txt .