e7f66fb2 fixed one problem and introduced a new one. Setting timestamps
after clearing_changes_information doesn't work, since using the
created_at and updated_at setters will change the object again. I added
some additional specs for this case (our only spec related to clearing
changes used an object without timestamps).
For the timezone problem, I did a little digging and realized the
casting behavior was actually correct. The reason it was behaving in a
different way than I was expecting is because we had
`time_zone_aware_attributes` set to false, whereas the AR railtie
[sets it to true](54652d886a/activerecord/lib/active_record/railtie.rb (L71)). Setting it to true causes date and datetime attributes
[to get decorated with a TimeZoneConverter](54652d886a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb (L68..L87))
f56394c187