We'll respond shortly.
Poltergeist is a gem that replaces capybara-webkit and handles iframes better supposedly. The unfortunate side-effect of using it is that it modifies how exception handling works even within your controller actions. This was incredibly hard to debug. We recommend not using it for a while.
If you have a nil time column and you set it to nil,
model.changed? now returns true.
The same is true for any values which are equal.