Let the method-combination sort methods that agree in specializers but not qualifiers

[fiddlerwoaroof]

CLHS 7.6.6.1.2+3 seem to specify that, when the specializers of two methods all agree but the qualifiers disagree, the method combination determines how the the ambiguity is resolved:

7.6.6.1.2: The corresponding parameter specializers from each method are compared. When a pair of parameter specializers agree, the next pair are compared for agreement. If all corresponding parameter specializers agree, the two methods must have different qualifiers; in this case, either method can be selected to precede the other.

7.6.6.1.3: The role of each method in the effective method is determined by its qualifiers and the specificity of the method. A qualifier serves to mark a method, and the meaning of a qualifier is determined by the way that these marks are used by this step of the procedure [method combination].

In this situation, SBCL throws an error saying that there is more than one method with the same specializers.

To reproduce:

(defpackage :mc-test
  (:use :cl )
  (:export ))
(in-package :mc-test)

(defun positive-integer-qualifier-p (method-qualifiers)
  (and (= (length method-qualifiers) 1)
       (typep (first method-qualifiers) '(integer 0 *))))
(define-method-combination example-method-combination ()
  ((methods positive-integer-qualifier-p))
  `(progn ,@(mapcar #'(lambda (method)
                        `(call-method ,method))
                    (stable-sort methods #'<
                                 :key #'(lambda (method)
                                          (first (method-qualifiers method)))))))
(defgeneric quux (a) (:method-combination example-method-combination))
(defmethod quux 0 (a) (format t "hi there"))
(defmethod quux 1 (a) (format t "bye?"))

(quux)