CI does a proper export. FINALLY.

lib/tasks/ci.rake

-desc "Run all specs and features"
-task :ci => [:environment] do
-  system "/etc/init.d/xvfb start"
-  system "DISPLAY=:99.0 bundle exec rake"
-  exit_status = $?.exitstatus
-  system "/etc/init.d/xvfb stop"
-  raise "tests failed!" unless exit_status == 0
-end
\ No newline at end of file
+namespace :ci do
+  desc "Run all specs and features"
+  task :ci => :environment do
+    system('/etc/init.d/xvfb start')
+    system('export DISPLAY=:99.0 && bundle exec rake')
+    exit_status = $?.exitstatus
+    system('/etc/init.d/xvfb stop')
+    raise "tests failed!" unless exit_status == 0
+  end
+end
+task :ci => "ci:ci"