title: devise confirmable not working in newest version
body: <p>I recently upgraded from Devise 1.2 to 1.4.9 and everything seems to work except my confirmable module. Email works as well as the entire process.  But the confirmation page is always blank.  It works and it confirms the email account, but it does not redirect the user and throws a 406 error.  It does the same for false confirmation attempts.</p>
  
  <p>Routes seem to work fine, I have confirmable specified in my user model, and nothing else has changed.</p>
  
  <p>Any ideas?  Am I missing some settings or something I need to update for 1.4.9?</p>
  
  <p>UPDATE</p>
  
  <p>It seems to be a problem with the URL being generated.  For some unknown reason it is prepending the confirmations URL with the user name? and that is causing it to break.  But i'm still not sure how to fix it.</p>
  
  <p><a href="http://localhost:5000/users/confirmation.someusername?confirmation_token=R7apAPhC5c3rszvhsowp" rel="noreferrer">http://localhost:5000/users/confirmation.someusername?confirmation_token=R7apAPhC5c3rszvhsowp</a></p>
  
  <p>The username in the URL above causes the process not to work.</p>
  
  <p>I checked the diff between the controller in 1.2 (which works) and the new version.</p>
  
  <h1>1.2</h1>
  
  <pre><code>  # GET /resource/confirmation?confirmation_token=abcdef
    def show
      self.resource = resource_class.confirm_by_token(params[:confirmation_token])
  
      if resource.errors.empty?
        set_flash_message :notice, :confirmed
        sign_in_and_redirect(resource_name, resource)
      else
        render_with_scope :new
      end
    end
  </code></pre>
  
  <h1>1.4.9</h1>
  
  <pre><code>  # GET /resource/confirmation?confirmation_token=abcdef
    def show
      self.resource = resource_class.confirm_by_token(params[:confirmation_token])
  
      if resource.errors.empty?
        set_flash_message(:notice, :confirmed) if is_navigational_format?
        sign_in(resource_name, resource)
        respond_with_navigational(resource){ redirect_to after_confirmation_path_for(resource_name, resource) }
      else
        respond_with_navigational(resource.errors, :status =&gt; :unprocessable_entity){ render_with_scope :new }
      end
    end
  
    protected
  
      # The path used after resending confirmation instructions.
      def after_resending_confirmation_instructions_path_for(resource_name)
        new_session_path(resource_name)
      end
  
      # The path used after confirmation.
      def after_confirmation_path_for(resource_name, resource)
        after_sign_in_path_for(resource)
      end
  </code></pre>
  
  <h1>error</h1>
  
  <pre><code>Started GET "/users/confirmation.sdfsdfsd?confirmation_token=vmxmx73xvM7sUfcvH9CX" for 127.0.0.1 at 2011-10-31 13:30:33 +0100
    Processing by Devise::ConfirmationsController#show as 
    Parameters: {"confirmation_token"=&gt;"vmxmx73xvM7sUfcvH9CX"}
    SQL (1.1ms)   SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc, a.attnotnull
   FROM pg_attribute a LEFT JOIN pg_attrdef d
   ON a.attrelid = d.adrelid AND a.attnum = d.adnum
   WHERE a.attrelid = '"users"'::regclass
   AND a.attnum &gt; 0 AND NOT a.attisdropped
   ORDER BY a.attnum
  
    User Load (1.2ms)  SELECT "users".* FROM "users" WHERE "users"."confirmation_token" = 'vmxmx73xvM7sUfcvH9CX' LIMIT 1
    SQL (0.7ms)   SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc, a.attnotnull
   FROM pg_attribute a LEFT JOIN pg_attrdef d
   ON a.attrelid = d.adrelid AND a.attnum = d.adnum
   WHERE a.attrelid = '"users"'::regclass
   AND a.attnum &gt; 0 AND NOT a.attisdropped
   ORDER BY a.attnum
  
  Completed 406 Not Acceptable in 28ms
  </code></pre>