// FIXME: there is a race condition here where two actors run Mailbox::byName
// on a non-existent mailbox during the same scheduling round. Both will be
// interrupted in the simcall creating the underlying simix mbox.
// FIXME: there is a race condition here where two actors run Mailbox::byName
// on a non-existent mailbox during the same scheduling round. Both will be
// interrupted in the simcall creating the underlying simix mbox.