rails-html-sanitizer gem breaks ActionMailer + ActionView + ActiveRecord - Rails 4.2.0 projects

demo.rb

require "active_record"
require "action_view/helpers"
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', dbfile: ':memory:')

# Alternative minimal implementation:
require "active_record"
require "action_mailer" 
ActionMailer::Base.delivery_method = :test
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', dbfile: ':memory:')

Gemfile

source "https://rubygems.org"

gem "activerecord", "= 4.2.0"
gem "actionview", "= 4.2.0"
gem "sqlite3"

output

$ bundle exec ruby demo.rb 
GEM_PATH/activerecord-4.2.0/lib/active_record/connection_handling.rb:3:in `block in <module:ConnectionHandling>': undefined method `env' for Rails:Module (NoMethodError)
        from GEM_PATH/activerecord-4.2.0/lib/active_record/connection_handling.rb:4:in `call'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/connection_handling.rb:4:in `block in <module:ConnectionHandling>'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/connection_handling.rb:63:in `call'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/connection_handling.rb:63:in `initialize'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/core.rb:46:in `new'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/core.rb:46:in `configurations='
        from GEM_PATH/activerecord-4.2.0/lib/active_record/core.rb:48:in `block in <module:Core>'
        from GEM_PATH/activesupport-4.2.0/lib/active_support/concern.rb:120:in `class_eval'
        from GEM_PATH/activesupport-4.2.0/lib/active_support/concern.rb:120:in `append_features'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/base.rb:285:in `include'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/base.rb:285:in `<class:Base>'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/base.rb:270:in `<module:ActiveRecord>'
        from GEM_PATH/activerecord-4.2.0/lib/active_record/base.rb:26:in `<top (required)>'
        from demo.rb:3:in `<main>'