Fix redirection to home page URL for unauthorized users

Redirection to the home page URL was broken by changing the target for
`root_url` from `DashboardController` to `RootController` in
94d3c143. This regression was introduced
in the 7.12.0 release.

Fixes #1916.

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 7.13.0 (unreleased)
+  - Fix redirection to home page URL for unauthorized users (Daniel Gerhardt)
   - Fix external issue tracker hook/test for HTTPS URLs (Daniel Gerhardt)
   - Remove link leading to a 404 error in Deploy Keys page (Stan Hu)
   - Add support for unlocking users in admin settings (Stan Hu)

app/controllers/application_controller.rb

@@ -56,7 +56,7 @@ class ApplicationController < ActionController::Base
   def authenticate_user!(*args)
     # If user is not signed-in and tries to access root_path - redirect him to landing page
     if current_application_settings.home_page_url.present?
-      if current_user.nil? && controller_name == 'dashboard' && action_name == 'show'
+      if current_user.nil? && root_path == request.path
         redirect_to current_application_settings.home_page_url and return
       end
     end