fix re-expansion of a simple #%module-body form with submodules

Closes #1538

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

@@ -1905,6 +1905,38 @@ case of module-leve bindings; it doesn't cover local bindings.
                                     (namespace-syntax-introduce 
                                      (dynamic-require ''provide-the-x-identifier 'x-id))))))
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Make sure that re-expansion of a simple (in the sense of `require`
+;; information kept for `module->namspace`) module body is ok
+
+(module m racket/base
+  (module mylang racket/base
+    (require (for-syntax racket/base))
+    (provide (rename-out [-#%module-begin #%module-begin]))
+    (define-syntax (-#%module-begin stx)
+      (syntax-case stx ()
+        [(_ lng . rest)
+         (with-syntax ([#%module-begin (datum->syntax #'lng '#%module-begin)])
+           #`(#%plain-module-begin
+              (require lng)
+              (continue #%module-begin . rest)))]))
+    (define-syntax (continue stx)
+      (syntax-case stx ()
+        [(_ lang-module-begin . rest)
+         (let ([body-stx (local-expand
+                          #'(lang-module-begin . rest)
+                          'module-begin
+                          (list))])
+           (syntax-case body-stx (#%plain-module-begin)
+             [(#%plain-module-begin . mod-body)
+              #`(begin . mod-body)]))])))
+
+  (module foo (submod ".." mylang) racket/base
+          (module a-submod racket/base
+            (define x 1)
+            (provide x))
+          (require 'a-submod)))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (report-errs)

racket/src/racket/src/module.c

@@ -8778,7 +8778,7 @@ static Scheme_Object *do_module_begin(Scheme_Object *orig_form, Scheme_Comp_Env
       }
     }
 
-    if (*all_simple_bindings && env->genv->module->rn_stx) {
+    if (*all_simple_bindings && env->genv->module->rn_stx && rec[drec].comp) {
       /* We will be able to reconstruct binding for `module->namespace`: */
       env->genv->module->rn_stx = scheme_true;
     } else {