When using reconfirmable, notify the original email about the change right away

Do not wait for the email change to be confirmed by the "unconfirmed
email" with reconfirmable: notify the original email right away.

lib/devise/models/confirmable.rb

@@ -277,6 +277,16 @@ module Devise
           confirmation_required? && !@skip_confirmation_notification && self.email.present?
         end
 
+        # With reconfirmable, notify the original email when the user first
+        # requests the email change, instead of when the change is confirmed.
+        def send_email_change_notification?
+          if self.class.reconfirmable
+            self.class.send_email_change_notification && reconfirmation_required?
+          else
+            super
+          end
+        end
+
         # A callback initiated after successfully confirming. This can be
         # used to insert your own logic that is only run after the user successfully
         # confirms.

test/models/confirmable_test.rb

@@ -516,4 +516,21 @@ class ReconfirmableTest < ActiveSupport::TestCase
     admin.save
     assert admin.pending_reconfirmation?
   end
+
+  test 'should notify previous email on email change when configured' do
+    swap Devise, send_email_change_notification: true do
+      admin = create_admin
+      original_email = admin.email
+
+      assert_difference 'ActionMailer::Base.deliveries.size', 2 do
+        assert admin.update_attributes(email: 'new-email@example.com')
+      end
+      assert_equal original_email, ActionMailer::Base.deliveries[-2]['to'].to_s
+      assert_equal 'new-email@example.com', ActionMailer::Base.deliveries[-1]['to'].to_s
+
+      assert_email_not_sent do
+        assert admin.confirm
+      end
+    end
+  end
 end