DEFUN ("system-users", Fsystem_users, Ssystem_users, 0, 0, 0,
doc: /* Return a list of user names currently registered in the system.
-The value may be nil if not supported on this platform. */)
+If we don't know how to determine that on this platform, just
+return a list with one element, taken from `user-real-login-name'. */)
(void)
{
Lisp_Object users = Qnil;