Fix sporadic redirect on /

Author: rewritten

app/controllers/application_controller.rb

@@ -52,6 +52,7 @@ def store_location
   end
 
   def after_sign_in_path_for(user)
+    session[:previous_url] = nil if session[:previous_url] == "/"
     session[:previous_url] || begin
       if user.members.present?
         users_path