Restore lookup formats to the previous value after searching for the failing view

actionpack/lib/action_view/template.rb

@@ -164,10 +164,12 @@ module ActionView
       pieces  = @virtual_path.split("/")
       name    = pieces.pop
       partial = !!name.sub!(/^_/, "")
-      lookup.formats = @formats
+      previous_formats, lookup.formats = lookup.formats, @formats
       lookup.disable_cache do
         lookup.find_template(name, [ pieces.join('/') ], partial, @locals)
       end
+    ensure
+      lookup.formats = previous_formats
     end
 
     def inspect

actionpack/test/template/render_test.rb

@@ -52,10 +52,11 @@ module RenderTestCases
   end
 
   def test_render_template_with_a_missing_partial_of_another_format
+    @view.lookup_context.freeze_formats([:html])
     assert_raise ActionView::Template::Error, "Missing partial /missing with {:locale=>[:en], :formats=>[:json], :handlers=>[:erb, :builder]}" do
-      @view.lookup_context.freeze_formats([:html])
       @view.render(:template => "with_format", :formats => [:json])
     end
+    assert_equal [:html], @view.lookup_context.formats
   end
 
   def test_render_file_with_locale