I just installed the OpenID plugin, 1.3 on Jenkins 1.413. After configuring "on the side" open id endpoints for my account, when I go to log in with OpenID, I do not see the provider selection interface, and if I manually enter my endpoint or username, I get the error "org.openid4java.discovery.DiscoveryException: 0x500: Cannot parse identifier: null".

Looking in Chrome developer tools and Firefox Firebug, I see that the openid javascript is actually not loading, it is returning a 403. I assume this is the cause of the failure. Jenkins is behind nginx, but I'm pretty sure the problem is not with nginx. I have no security applied in nginx, and the Winstone header is returned in the 403 response "X-Powered-By: Servlet/2.5 (Winstone/0.9.10)".