ActiveRecord rename index error for MariaDB 10

bug_test.rb

gem 'activerecord', '4.1.2'
gem 'mysql2'
require 'active_record'
require 'minitest/autorun'
require 'logger'

DATABASE_NAME = 'rename_index_test'

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

ActiveRecord::Base.establish_connection(adapter: 'mysql2', database: DATABASE_NAME)
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
  end

  create_table :comments, force: true do |t|
    t.integer :post_id
  end

  add_index :comments, :post_id, name: "comments_post_index"
end

class RenamePostIndex < ActiveRecord::Migration
  def change
    change_table :comments do |t|
      t.rename_index :comments_post_index, :comments_post_id_index
    end
  end
end

class BugTest < Minitest::Test
  def test_rename_index
    # Raises ActiveRecord::StatementInvalid: Mysql2::Error: You have an error in your SQL syntax;
    #   check the manual that corresponds to your MariaDB server version for the right syntax to
    #   use near 'INDEX `comments_post_index` TO `comments_post_id_index`' at line 1: ALTER TABLE
    #   `comments` RENAME INDEX `comments_post_index` TO `comments_post_id_index`
    RenamePostIndex.new.change
  end
end

Gemfile

source 'https://rubygems.org'

gem 'activerecord', '4.1.2'
gem 'mysql2'