Modifications to User Controller and Login View generated by SaltedHashGenerator not working as expected

I have modified signup.rhtml to send an Ajax request (by having a form_remote_tag), to signup method of controller.
In signup method “puts request.xhr?” always prints false at the console.

To verify, I added a test method in controller and tried to call it using form_remote_tag from view results in a get request.

What component of salted hash generator is modifying the request object?