Incorrect result from some simple code

[Paul F. Dietz]

(defun bug231 ()
  (let* ((form
           '(let ((v1 (if (not nil) 10 20)))
             (decf v1 (/ v1 1))))
         (lam1 `(lambda () ,form))
         (lam2 `(lambda ()
                  (declare (notinline not))
                  (declare (optimize (debug 2)))
                  ,form)))
    (values (funcall (compile nil lam1))
            (funcall (compile nil lam2)))))

(bug231) ==> 0, 10 ; 0 is correct

x86-64, "2.3.8.133-16a213255"

[Stas Boukarev (stassats)]

Got incidentally fixed by the reworking in d31534468a43a728b4c3e07fd58289a1fabb79ef