Allow layout rendering to access current object being rendered when using partial + collection

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -283,12 +283,18 @@ module ActionView
       end
 
       if layout = @options[:layout]
-        layout = find_template(layout)
+        layout = find_template(layout, @locals.keys + [@variable])
       end
 
       result = @template ? collection_with_template : collection_without_template
 
-      result.map!{|content| layout.render(@view, @locals) { content } } if layout
+      if layout
+        locals = @locals
+        result.map! do |content|
+          locals[@variable] = @collection[result.index(content)]
+          layout.render(@view, @locals) { content }
+        end
+      end
 
       result.join(spacer).html_safe
     end
@@ -395,7 +401,6 @@ module ActionView
       segments
     end
 
-
     def collection_without_template
       segments, locals, collection_data = [], @locals, @collection_data
       index, template, cache = -1, nil, {}

actionpack/test/fixtures/test/_b_layout_for_partial_with_object.html.erb

@@ -0,0 +1 @@
+<b class="<%= customer.name.downcase %>"><%= yield %></b>

actionpack/test/template/render_test.rb

@@ -238,6 +238,10 @@ module RenderTestCases
     assert_equal "<b>Hello: Amazon</b><b>Hello: Yahoo</b>", @view.render(:partial => "test/customer", :layout => 'test/b_layout_for_partial', :collection => [ Customer.new("Amazon"), Customer.new("Yahoo") ])
   end
 
+  def test_render_partial_with_layout_using_collection_and_template_makes_current_item_available_in_template
+    assert_equal '<b class="amazon">Hello: Amazon</b><b class="yahoo">Hello: Yahoo</b>', @view.render(:partial => "test/customer", :layout => 'test/b_layout_for_partial_with_object', :collection => [ Customer.new("Amazon"), Customer.new("Yahoo") ])
+  end
+
   def test_render_partial_with_empty_array_should_return_nil
     assert_nil @view.render(:partial => [])
   end