Misunderstanding of :inverse_of?

gistfile1.rb

class User < ActiveRecord::Base
  has_many :emails, :inverse_of => :user
end

class Email < ActiveRecord::Base
  belongs_to :user , :inverse_of => :emails
end

# spec 1
u = User.find(1)
e = u.emails.first
# fails in Rails 3.0 and Rails 3.1
# but I expect it to pass!
u.object_id.should == e.user.object_id

# spec 2
u = User.find(1, :include => :emails)
e = u.emails.first
# fails in Rails 3.0 but passes in Rails 3.1
u.object_id.should == e.user.object_id