expander: fix code-inspector management during macro expansion

Specifically, don't incorrectly preserve the current macro's code
inspector when triggering another macro via `local-expand`.

pkgs/racket-test-core/tests/racket/macro.rktl

@@ -2119,6 +2119,42 @@
 
 (test 42 dynamic-require ''parent-internal-definition-contexts-do-add-bindings 'result)
 
+;; ----------------------------------------
+;; Make sure that changing the code expander disables syntax
+;; disarming when it should
+
+(parameterize ([current-namespace (make-base-namespace)]
+               [current-code-inspector (current-code-inspector)])
+
+  (eval
+   '(module disarm racket/base
+      (require (for-template racket/base))
+      (define (disarm s)
+        (unless (syntax-tainted? (car (syntax-e (syntax-disarm s #f))))
+          (error "disarm suceeded!"))
+        #''ok)
+      (provide disarm)))
+
+  (eval
+   '(module mapply racket/base
+      (require (for-syntax racket/base))
+      (provide mapply)
+      (define-syntax (mapply stx)
+        (syntax-case stx ()
+          [(_ m) #`(m #,(syntax-protect #'(x)))]))))
+
+  (current-code-inspector (make-inspector (current-code-inspector)))
+
+  (eval
+   '(module orig racket/base
+      (require (for-syntax racket/base
+                           'disarm)
+               'mapply)
+      (define-syntax (m stx)
+        (syntax-case stx ()
+          [(_ e) (disarm #'e)]))
+      (mapply m))))
+
 ;; ----------------------------------------
 
 (report-errs)

racket/src/expander/expand/main.rkt

@@ -424,7 +424,7 @@
                    [current-namespace (namespace->namespace-at-phase
                                        (expand-context-namespace ctx)
                                        (add1 (expand-context-phase ctx)))]
-                   [current-module-code-inspector (or insp-of-t (current-module-code-inspector))])
+                   [current-module-code-inspector (or insp-of-t #;(current-module-code-inspector))])
       (call-with-continuation-barrier
        (lambda ()
          ;; Call the transformer!