Avoid adding the same items multiple times into the same menu

[21](LaLogiaDePython#21)

menu_generator/templatetags/menu_generator.py

@@ -20,7 +20,9 @@ def get_menu(context, menu_name):
     :param menu_name: String, name of the menu to be found
     :return: Generated menu
     """
-    menu_list = getattr(settings, menu_name, defaults.MENU_NOT_FOUND)
+     # Instantiate a new list() or else the same instance of the menu_list gets used over and over
+    # (and possibly re-adding the menu_from_apps list on each request)
+    menu_list = list(getattr(settings, menu_name, defaults.MENU_NOT_FOUND))
     menu_from_apps = get_menu_from_apps(menu_name)
     # If there isn't a menu on settings but there is menu from apps we built menu from apps
     if menu_list == defaults.MENU_NOT_FOUND and menu_from_apps:

menu_generator/tests/test_menu.py

@@ -351,4 +351,14 @@ def test_generate_menu_selected_related_views_submenu(self):
         self.assertEqual(len(nav), 1)
         self.assertEqual(nav[0]["selected"], True)
         self.assertEqual(nav[0]["submenu"][0]["selected"], True)
-        self.assertEqual(nav[0]["submenu"][1]["selected"], False)
+        self.assertEqual(nav[0]["submenu"][1]["selected"], False)
+
+    def test_subsequent_requests(self):
+        self.request.user = TestUser(authenticated=True)
+        ctx = {
+            'request': self.request
+        }
+        nav1 = get_menu(ctx, 'NAV_MENU')
+        nav2 = get_menu(ctx, 'NAV_MENU')
+        # Both menus should be equal
+        self.assertEqual(nav1, nav2)