I found a red Jenkins build with no test failures, the problem might not be immediately clear. In the logs I find this, which seems to be the cause of the build failure:
Feature: Loading pages
Background: # features/page_loading.feature:4
Given the page "Selenium page loading test" exists # features/step_definitions/create_page_api_steps.rb:42
Scenario: Page loads without ajax in stable # features/page_loading.feature:7
Given I visit a protected page # features/step_definitions/create_page_api_steps.rb:86
Undefined step: "The "Selenium protected test 2" page is protected." (Cucumber::Undefined)
/scratch/jenkins/addons/ruby/ruby-2.1.1-x86_64/lib/ruby/gems/2.1.0/gems/cucumber-1.3.14/lib/cucumber/runtime/support_code.rb:145:in `step_match_without_cache'
https://wmf.ci.cloudbees.com/job/MobileFrontend-en.m.wikipedia.beta.wmflabs.org-linux-firefox/601/console