anchor.diff:        (setf (wfo-links wfo) (cdr link))
         (setf (cdr link) (event-waiters event)
               (event-waiters event) link)))
  +  ;; Set LINKS to :SLEEP-IN-PROGRESS to indicate that events were registered
  +  ;; with and WFO-UNREGISTER must be run.
  +  ;; See the big comment in WFO-WAIT.
  +  (setf (wfo-links wfo) :sleep-in-progress)
     ;; Now go to sleep, zzz.
     (let ((self (current-thread)))
       (lock-wait-queue wfo)
  
positive.code:                             wfo)))
              (when completed
                (return completed)))
         ;; There are 4 ways to end up here:
         ;; 1) Normal return from WFO-WAIT-1 with completed events.
         ;; 2) Normal return without any completed events.
         ;; 3) Interrupted sleep, via normal return from the wfo unsleep helper.
         ;; 4) Interrupted sleep, via unwind.
         ;; Cases 2,3,4 are all effectively identical: WFO-WAIT-1 registered
         ;; the WFO with events and went to sleep. The WFO must be unregistered
         ;; from the events.
         ;; Case 1 is special: WFO-WAIT-1 did not register with any events and
         ;; WFO-UNREGISTER must *not* be called.
         ;; UNWIND-PROTECT catches case 4, cases 2 and 3 could be done in
         ;; the loop without an unwind protect. UNWIND-PROTECT screws over
         ;; case 1, so a specific test is required to avoid this.
         ;; WFO-LINKS is set to :COMPLETED when WFO-WAIT-1 picks up & returns
         ;; completed events. This is set in WFO-WAIT-1 - not in the WHEN above -
         ;; to avoid racing with further footholds (interrupts are disabled).
         (when (not (eql (wfo-links wfo) :completed))
           (wfo-unregister wfo)))))
  
  (defun wait-for-objects (&rest objects)
  
negative.code:     (when completed
        ;; There were some completed events.
        (release-place-spinlock *big-wait-for-objects-lock*)
        (return-from wfo-wait-1 completed)))
    ;; Register our wait queue with each event.
    (dolist (event (wfo-events wfo))
  