ActiveRecord::Dirty methods do not use nilify_blanks logic

[chrisdpeters]

Not sure if this is pushing too far, but I get incorrect behavior when trying to use methods like changed? and changes when nilify_blanks is applied to a model.

For example:

--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess
email:
- 
- ''
notes:
- 
- ''

I had to configure nilify_blanks like this:

nilify_blanks before: :validation

And then do this clunky logic to work around this problem:

# Save referral. We want to track if anything changed to decide how to treat any comments below.
referral.attributes = referral_attributes
# Force nilify_blanks to do its thing before validation so we can check for the true changes.
referral.valid?
# See if there were changes before updating the referral record. (This will always be `false` after we run
# `update`.)
referral_changed = referral.changed?
referral.save

Not sure how involved it would be to fix this or if it would be appropriate to do so. Or is there a better way to do what I'm trying to accomplish?