rosenfeld/sequel-devise — pull request #9 by andreychernih (2014-08-27 10:13:28+00:00)
Title: Make sure e-mail validation works for new records as well

sequel's dirty plugin differs from ActiveRecord::Dirty. It does not marks column changed when initializing new records:

user = User.new email: 'my@email.com'
user.column_changed?(:email) # => false