fix console --sandbox

Ticket at #1194

As first described on Rails talk, script/console -s gives the error:

.../vendor/rails/activerecord/lib/active_record/base.rb:1824:in `method_missing':NoMethodError: undefined method `increment_open_transactions' for ActiveRecord::Base:Class

on Edge. I’ll also add that it doesn’t roll back transactions.

Ticket has a patch - very simple. Should probably go in 2.2, as the current version is dangerous (not rolling back).

–Matt

Pushed to edge and 2.1 branch.

Thanks.