Fix render partial with layout and no block

When using a render :partial with :layout call, without giving a block,
if the given :partial had another render :partial call, the layout was
not being rendered. This commit fixes this context by storing variables
before rendering the partial, so they are not overrided in any successive
call to render partials down the path. All ActionPack tests are ok.

actionpack/test/fixtures/test/_partial_with_partial.erb

@@ -0,0 +1,2 @@
+<%= render 'test/partial' %>
+partial with partial

actionpack/test/template/render_test.rb

@@ -267,6 +267,16 @@ module RenderTestCases
       @view.render(:layout => "layouts/partial_and_yield") { "Content from block!" }
   end
 
+  def test_render_partial_and_layout_without_block_with_locals
+    assert_equal %(Before (Foo!)\npartial html\nAfter),
+      @view.render(:partial => 'test/partial', :layout => 'test/layout_for_partial', :locals => { :name => 'Foo!'})
+  end
+
+  def test_render_partial_and_layout_without_block_with_locals_and_rendering_another_partial
+    assert_equal %(Before (Foo!)\npartial html\npartial with partial\n\nAfter),
+      @view.render(:partial => 'test/partial_with_partial', :layout => 'test/layout_for_partial', :locals => { :name => 'Foo!'})
+  end
+
   def test_render_with_nested_layout
     assert_equal %(<title>title</title>\n\n<div id="column">column</div>\n<div id="content">content</div>\n),
       @view.render(:file => "test/nested_layout.erb", :layout => "layouts/yield")