The work as done in bug 1157868 is not doing what it should do. Instead of comparing the loaded page with the target page, we now compare the target page with itself. I will have a look at this.
Talked with gcp on IRC and the underlying problem is in Firefox. So the landing of the change is even only a wallpaper which hides the real behavior of Firefox. The change in Firefox has been landed via bug 1147212. It means we do not have to differentiate between phishing and malware anymore. We always redirect to SUMO now: https://hg.mozilla.org/mozilla-central/rev/8b191f5f9687#l4.65
Created attachment 8602161 [details] [review] github_pull_request.txt
Somehow this change got reverted end of May so it was causing failures of the recent RC of Firefox 40.0 on the mozilla-release branch: https://treeherder.allizom.org/#/jobs?repo=mozilla-release&revision=a61c2305edd9 I re-landed it so tests should pass again: https://github.com/mozilla/firefox-ui-tests/commit/3d760b3571d019f6d0cf39c19f2b9ecf96f9a113