Rails 5 increment! does not invoke callbacks

increment_test.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  # Activate the gem you are reporting the issue against.
  gem "activerecord", "5.0.0.1"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

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

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :comments, force: true do |t|
    t.integer :sheets
    t.string :description
  end
end

class Comment < ActiveRecord::Base
  after_save :update_description

  def update_description
    update_column(:description, "#{sheets.to_i} Sheets")
  end
end

class BugTest < Minitest::Test
  def test_increment
    comment = Comment.create!
    assert_equal comment.description, "0 Sheets"

    comment.increment!(:sheets, 1)
    assert_equal comment.description, "1 Sheets"
  end
end