7 files changed, 34 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index cd6c6f8d1f..0bf0b37900 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -11,7 +11,7 @@ module ActiveRecord
 
     def includes(*args)
       args.reject! { |a| a.blank? }
-      clone.tap {|r| r.includes_values += args if args.present? }
+      clone.tap {|r| r.includes_values = (r.includes_values + args).flatten.uniq if args.present? }
     end
 
     def eager_load(*args)
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 02db8d2b89..f857e50dea 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -8,7 +8,13 @@ module ActiveRecord
 
       ((Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS) - [:joins, :where]).each do |method|
         value = r.send(:"#{method}_values")
-        merged_relation.send(:"#{method}_values=", value) if value.present?
+        if value.present?
+          if method == :includes
+            merged_relation = merged_relation.includes(value)
+          else
+            merged_relation.send(:"#{method}_values=", value) 
+          end
+        end
       end
 
       merged_relation = merged_relation.joins(r.joins_values)
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index ac7b501bb7..bcc36d79be 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -10,10 +10,20 @@ require 'models/entrant'
 require 'models/developer'
 require 'models/company'
 require 'models/bird'
+require 'models/car'
+require 'models/engine'
+require 'models/tyre'
+
 
 class RelationTest < ActiveRecord::TestCase
   fixtures :authors, :topics, :entrants, :developers, :companies, :developers_projects, :accounts, :categories, :categorizations, :posts, :comments,
-    :taggings
+    :taggings, :cars
+
+  def test_two_named_scopes_with_includes_should_not_drop_any_include
+    car = Car.incl_engines.incl_tyres.first
+    assert_no_queries { car.tyres.length } 
+    assert_no_queries { car.engines.length } 
+  end
 
   def test_apply_relation_as_where_id
     posts = Post.arel_table
diff --git a/activerecord/test/models/author.rb b/activerecord/test/models/author.rb
index 727978431c..34bfd2d881 100644
--- a/activerecord/test/models/author.rb
+++ b/activerecord/test/models/author.rb
@@ -93,6 +93,9 @@ class Author < ActiveRecord::Base
   belongs_to :author_address, :dependent => :destroy
   belongs_to :author_address_extra, :dependent => :delete, :class_name => "AuthorAddress"
 
+  scope :relation_include_posts, includes(:posts)
+  scope :relation_include_tags, includes(:tags)
+
   attr_accessor :post_log
   after_initialize :set_post_log
 
diff --git a/activerecord/test/models/car.rb b/activerecord/test/models/car.rb
index 1101180a67..faf4e6cbc0 100644
--- a/activerecord/test/models/car.rb
+++ b/activerecord/test/models/car.rb
@@ -1,4 +1,9 @@
 class Car < ActiveRecord::Base
+  has_many :tyres
   has_many :engines
   has_many :wheels, :as => :wheelable
+
+  scope :incl_tyres, includes(:tyres)
+  scope :incl_engines, includes(:engines)
+
 end
diff --git a/activerecord/test/models/tyre.rb b/activerecord/test/models/tyre.rb
new file mode 100644
index 0000000000..bc3444aa7d
--- /dev/null
+++ b/activerecord/test/models/tyre.rb
@@ -0,0 +1,3 @@
+class Tyre < ActiveRecord::Base
+  belongs_to :car
+end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index fc3810f82b..c72f7b25ca 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -194,6 +194,10 @@ ActiveRecord::Schema.define do
     t.integer :car_id
   end
 
+  create_table :tyres, :force => true do |t|
+    t.integer :car_id
+  end
+
   create_table :entrants, :force => true do |t|
     t.string  :name, :null => false
     t.integer :course_id, :null => false