anchor.diff:                   (setf (cdr push-cons) (thread-pending-footholds thread)
                          (thread-pending-footholds thread) push-cons)))))
         (cond ((eql thread (current-thread))
  -             (cond ((eql (thread-inhibit-footholds thread) 0)
  +             (cond ((or force
  +                        (eql (thread-inhibit-footholds thread) 0))
                       (funcall function))
                      (t
                       (push-foothold))))
  
positive.code:                             (thread-unsleep-helper thread)
                              (thread-unsleep-helper-argument thread)))))
  
  (defun establish-thread-foothold (thread function)
    (check-type thread thread)
    (check-type function function)
    (assert (not (member (thread-priority thread) '(:idle :supervisor))))
  
negative.code:                (cond ((eql (thread-state thread) :dead)
                        ;; Thread is dead, do nothing.
                        nil)
                       ((or force
                            (eql (thread-inhibit-footholds thread) 0))
                        (unsleep-thread thread)
                        (force-call-on-thread thread function))
                       (t
  