Under signal/signal.c the comment header states the following:

/* Set the handler for the signal SIG to HANDLER,
returning the old handler, or SIG_ERR on error. */

Yet the function doesn't return the old handler at any point, it only returns SIG_ERR.
Is my understanding correct? If so, is the comment wrong and should be corrected?
I understand that using signal() is to be avoided and I should use sigaction instead.

__sighandler_t
signal (int sig, __sighandler_t handler)
{
__set_errno (ENOSYS);
return SIG_ERR;}

Thanks,
-Firas