Merge branch 'active_model_unused_variable' of...

Merge branch 'active_model_unused_variable' of https://github.com/pacoguzman/rails into pacoguzman-active_model_unused_variable

activemodel/lib/active_model/observing.rb

@@ -72,7 +72,7 @@ def count_observers
         def instantiate_observer(observer) #:nodoc:
           # string/symbol
           if observer.respond_to?(:to_sym)
-            observer = observer.to_s.camelize.constantize.instance
+            observer.to_s.camelize.constantize.instance
           elsif observer.respond_to?(:instance)
             observer.instance
           else