@fabpot sorry, but I don't understand about what other occurrences you say.
maybe did you mean this:
https://github.com/Olden/symfony/blob/cb9b57c4f170e4670b7b5773e92c808ed933bf94/src/Symfony/Component/HttpKernel/Debug/TraceableEventDispatcher.php#L414

and this:
https://github.com/Olden/symfony/blob/cb9b57c4f170e4670b7b5773e92c808ed933bf94/src/Symfony/Component/HttpKernel/Debug/TraceableEventDispatcher.php#L425