I had to bump the version beyond the 1.580 bump in PR11 to handle JENKINS-25019. The left over failures would be related to this.
Unfortunately, the problems left over from this pom bump are not related to the issues that I found earlier. I have actually fixed those issues. The new issue is actually related to serving up the openid xrds.jelly; either it can't be found or the proxy service is in error (fakeproxy.jenkins-ci.org: Name or service not known). This might be related to the move from jenkins-ci.org which I think the maintainer of the plugin should deal with. The "not found 404" errors I'm seeing I think relate to the actual location of the xrds.jelly file. JenkinsRule changed a bunch of things around with accessing files, and this is one of the things that was affected by that.