title: Where default protocol is configured for rails `link_to`?
body: <p>Rails <code>link_to</code> generates a link with <code>http://</code> prfeix. But site is <code>https</code>.</p>
  <p>So forms must not be used like so. And actually it is not working for most browsers.</p>
  <p>The problem appears in <code>spree</code> shop. Internal templates of <code>spree</code> generates wrong urls. So modify <code>spree</code> internal templates to add protocol to each <code>link_to</code> is not a solution.</p>
  <p>Where default protocol is configured for rails <code>link_to</code>?</p>