Revert "Fix find_in_batches with customized primary_key"

This reverts commit 761bc751d31c22e2c2fdae2b4cdd435b68b6d783.

This commit wasn't fixing any issue just using the same table for
different models with different primary keys.

2 files changed, 5 insertions, 6 deletions

diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index 3b4ff83725..78d89aa232 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -125,14 +125,18 @@ class EachTest < ActiveRecord::TestCase
   end
 
   def test_find_in_batches_should_use_any_column_as_primary_key
+    old_primary_key  = Post.primary_key
+    Post.primary_key = :title
     title_order_posts = Post.order('title asc')
     start_title = title_order_posts.first.title
 
     posts = []
-    PostWithTitlePrimaryKey.find_in_batches(:batch_size => 1, :start => start_title) do |batch|
+    Post.find_in_batches(:batch_size => 1, :start => start_title) do |batch|
       posts.concat(batch)
     end
 
     assert_equal title_order_posts.map(&:id), posts.map(&:id)
+  ensure
+    Post.primary_key = old_primary_key
   end
 end
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 9858f68c4a..c995f59a15 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -186,8 +186,3 @@ class SpecialPostWithDefaultScope < ActiveRecord::Base
   self.table_name = 'posts'
   default_scope { where(:id => [1, 5,6]) }
 end
-
-class PostWithTitlePrimaryKey < ActiveRecord::Base
-  self.table_name = 'posts'
-  self.primary_key = :title
-end