Improve reliability of asserting that there are no 404-errors

Author: mdmintz

seleniumbase/fixtures/base_case.py

@@ -2758,7 +2758,12 @@ def assert_link_status_code_is_not_404(self, link):
     def __get_link_if_404_error(self, link):
         status_code = str(self.get_link_status_code(link))
         if status_code == "404":
-            return link
+            # Verify again to be sure. (In case of multi-threading overload.)
+            status_code = str(self.get_link_status_code(link))
+            if status_code == "404":
+                return link
+            else:
+                return None
         else:
             return None