Merge branch...

Merge branch '5699-enabling-disabling-features-does-not-propagate-correctly-to-geo-secondaries' into 'master'

Backport a refactor on the Feature.flipper method to CE

See merge request gitlab-org/gitlab-ce!22152

lib/feature.rb

@@ -72,7 +72,11 @@ class Feature
     end
 
     def flipper
-      @flipper ||= (Gitlab::SafeRequestStore[:flipper] ||= build_flipper_instance)
+      if Gitlab::SafeRequestStore.active?
+        Gitlab::SafeRequestStore[:flipper] ||= build_flipper_instance
+      else
+        @flipper ||= build_flipper_instance
+      end
     end
 
     def build_flipper_instance