NoMethodError when listing resource using rails 3.2.1

[jjnevis]

Using the same code, but updating the gemfile to use rails 3.2.1 I get the following error when I try to list the products:

NoMethodError in ProductsController#index

undefined method `merge' for #<Array:0x2388860>
Rails.root: /Users/jay/work/dev/simple-rails-multi-tenancy

Application Trace | Framework Trace | Full Trace
activerecord (3.2.1) lib/active_record/relation.rb:500:in `with_default_scope'
activerecord (3.2.1) lib/active_record/relation.rb:166:in `exec_queries'
activerecord (3.2.1) lib/active_record/relation.rb:159:in `block in to_a'
activerecord (3.2.1) lib/active_record/explain.rb:40:in `logging_query_plan'
activerecord (3.2.1) lib/active_record/relation.rb:158:in `to_a'
activerecord (3.2.1) lib/active_record/relation/finder_methods.rb:159:in `all'
activerecord (3.2.1) lib/active_record/querying.rb:5:in `all'
app/controllers/products_controller.rb:5:in `index'
actionpack (3.2.1) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.1) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.1) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.1) lib/active_support/callbacks.rb:415:in `block in _run__296475404__process_action__1005153655__callbacks'
activesupport (3.2.1) lib/active_support/callbacks.rb:215:in `block in _conditional_callback_around_22'
app/controllers/application_controller.rb:11:in `block in with_tenant'
app/models/tenant.rb:16:in `with'
app/controllers/application_controller.rb:11:in `with_tenant'
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