Do not send id for quoting twice if the primary key is string.

[#6022 state:resolved]

activerecord/lib/active_record/relation/predicate_builder.rb

@@ -26,7 +26,8 @@ module ActiveRecord
           when Range, Arel::Relation
             attribute.in(value)
           when ActiveRecord::Base
-            attribute.eq(value.quoted_id)
+            sanitized_id = attribute.class == Arel::Attributes::String ? value.id : value.quoted_id
+            attribute.eq(sanitized_id)
           when Class
             # FIXME: I think we need to deprecate this behavior
             attribute.eq(value.name)

activerecord/test/cases/relations_test.rb

@@ -14,11 +14,18 @@ require 'models/bird'
 require 'models/car'
 require 'models/engine'
 require 'models/tyre'
+require 'models/minivan'
 
 
 class RelationTest < ActiveRecord::TestCase
   fixtures :authors, :topics, :entrants, :developers, :companies, :developers_projects, :accounts, :categories, :categorizations, :posts, :comments,
-    :tags, :taggings, :cars
+    :tags, :taggings, :cars, :minivans
+
+  def test_do_not_double_quote_string_id
+    van = Minivan.last
+    assert van
+    assert_equal van.id, Minivan.where(:minivan_id => van).to_a.first.minivan_id
+  end
 
   def test_bind_values
     relation = Post.scoped