anchor.diff:      (unwind-protect
           (progn
             (unless *listening-signal-p* ;; called only on the toplevel stack
  -            #+debug
  -            (bt:with-lock-held (*handler-lock*)
  -              (format t "~&Registering the current thread as a listener: ~a"
  -                      (bt:current-thread))
  -              (force-output))
               (bt:with-lock-held (*listener-threads-lock*)
                 (setf (gethash (bt:current-thread) *listener-threads*) t)))
             ;; Only the additional signals are enabled.  It is possible
             ;; that a new signal is received while partly enabling these
             ;; signals before running ,@forms ...
  -          #+debug
  -          (bt:with-lock-held (*handler-lock*)
  -            (format t "~&Enabling signal handlers: ~a"
  -                    (bt:current-thread)))
             (%enable-all-signal-handlers next-enabled-signals)
             (let* ((*listening-signal-p* t))
               #+ccl
  
positive.code: ;; internally. Therefore, binding some of them may cause the implimentation
  ;; to malfunction.  (6. Signal handling,
  ;; http://www.sbcl.org/sbcl-internals/index.html)
  
  #+debug
  (defvar *handler-lock* (bt:make-lock "handler-lock")
    "force the handler processing to be synchronous")
  
  (define-condition unix-signal ()
    ((signo :initarg :signo :reader signo))
  
negative.code:        (bt:thread-name (bt:current-thread)))
        #-(or sbcl ccl)
        t
      (dolist (th (bt:all-threads)) ;; only the live threads
        (when (gethash th *listener-threads*)
          (bt:interrupt-thread th #'invoke-handlers signo)))))
  
  (defun invoke-handlers (signo)
    "Handler-invoking procedure per thread"
    (progn
      (dolist (handlers/layer *signal-handler-hierarchy*)
        (let ((handlers/signo (assocdr signo handlers/layer)))
          (when handlers/signo
  