- added ActionView::PartialRenderer#merge_path_into_partial(path, partial)

  fix issues/1951

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -362,14 +362,28 @@ def collection_without_template
     def partial_path(object = @object)
       @partial_names[object.class.name] ||= begin
         object = object.to_model if object.respond_to?(:to_model)
-
         object.class.model_name.partial_path.dup.tap do |partial|
           path = @lookup_context.prefixes.first
-          partial.insert(0, "#{File.dirname(path)}/") if partial.include?(?/) && path.include?(?/)
+          merge_path_into_partial(path, partial)
         end
       end
     end
 
+    def merge_path_into_partial(path, partial)
+      if path.include?(?/) && partial.include?(?/)
+        overlap = []
+        path_array = File.dirname(path).split('/')
+        partial_array = partial.split('/')[0..-3] # skip model dir & partial
+
+        path_array.each_with_index do |dir, index|
+          overlap << dir if dir == partial_array[index]
+        end
+
+        partial.gsub!(/^#{overlap.join('/')}\//,'')
+        partial.insert(0, "#{File.dirname(path)}/")
+      end
+    end
+
     def retrieve_variable(path)
       variable = @options[:as].try(:to_sym) || path[%r'_?(\w+)(\.\w+)*$', 1].to_sym
       variable_counter = :"#{variable}_counter" if @collection

actionpack/test/controller/render_test.rb

@@ -17,7 +17,7 @@ def nested_partial_with_form_builder
 module Quiz
   class QuestionsController < ActionController::Base
     def new
-      render :partial => Quiz::Question.new(:name => "Bruce Lee")
+      render :partial => Quiz::Question.new("Namespaced Partial")
     end
   end
 end