Rails 3.1.* bug

article.rb

class Article < ActiveRecord::Base
  has_many :comments
end

article_test.rb

require_relative '../test_helper'

class ArticleTest < ActiveSupport::TestCase
  def check_table_count(count, relation)
    assert_equal count, relation.instance_eval { tables_in_string(to_sql).size }
  end

  def test_plain
    check_table_count(1, Article.where(:title => 'foo.bar.baz'))
  end

  def test_includes
    check_table_count(1, Article.includes(:comments))
  end

  def test_includes_with_dots
    check_table_count(1, Article.where(:title => 'foo.bar.baz').includes(:comments))
  end

  def test_includes_with_conditions_on_join
    check_table_count(2, Article.where('comments.approved = 1').includes(:comments))
  end
end

comment.rb

class Comment < ActiveRecord::Base
  belongs_to :article
end

console.rb

ruby-1.9.2-p290 :004 > rel1 = Article.where(:title => 'foo').includes(:comments)
  Article Load (0.4ms)  SELECT "articles".* FROM "articles" WHERE "articles"."title" = 'foo'
 => [] 
ruby-1.9.2-p290 :005 > rel1.instance_eval { tables_in_string(to_sql) }
 => ["articles"] 
ruby-1.9.2-p290 :006 > rel2 = Article.where(:title => 'foo.bar').includes(:comments)
  SQL (0.3ms)  SELECT "articles"."id" AS t0_r0, "articles"."title" AS t0_r1, "comments"."id" AS t1_r0, "comments"."article_id" AS t1_r1 FROM "articles" LEFT OUTER JOIN "comments" ON "comments"."article_id" = "articles"."id" WHERE "articles"."title" = 'foo.bar'
 => [] 
ruby-1.9.2-p290 :007 > rel2.instance_eval { tables_in_string(to_sql) }
 => ["articles", "foo"] 

migrate.rb

class CreateArticlesAndComments < ActiveRecord::Migration
  def change
    create_table :articles
    create_table :comments do |t|
      t.belongs_to :article
    end
  end
end

patch.diff

diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 30f1824..d7335f3 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -528,7 +528,13 @@ module ActiveRecord
       return [] if string.blank?
       # always convert table names to downcase as in Oracle quoted table names are in uppercase
       # ignore raw_sql_ that is used by Oracle adapter as alias for limit/offset subqueries
-      string.scan(/([a-zA-Z_][.\w]+).?\./).flatten.map{ |s| s.downcase }.uniq - ['raw_sql_']
+      candidates = string.scan(/([a-zA-Z_][.\w]+).?\./).flatten.map{ |s| s.downcase }.uniq - ['raw_sql_']
+      candidates.reject do |t|
+        s = string.partition(t).first
+        s.chop! if s.last =~ /['"]/
+        s.reverse!
+        s =~ /^\s*=/
+      end
     end
   end
 end