scribble/base: fix problem with macro-introduced `include-section'

original commit: 4fd0d7454bd6392d97e2c5d1b917de34c13c6c48

pkgs/scribble-pkgs/scribble-lib/scribble/base.rkt

@@ -118,14 +118,14 @@
 (define-syntax (include-section stx)
   (syntax-case stx ()
     [(_ mod)
-     (with-syntax ([mod (syntax-local-introduce #'mod)])
+     (with-syntax ([doc-from-mod (datum->syntax #'mod 'doc)])
        (unless (module-path? (syntax->datum #'mod))
          (raise-syntax-error #f
                              "not a module path"
                              stx
                              #'mod))
        #'(begin
-           (require (only-in mod doc))
+           (require (only-in mod [doc-from-mod doc]))
            doc))]))
 
 ;; ----------------------------------------

pkgs/scribble-pkgs/scribble-test/tests/scribble/docs/include-section.scrbl

@@ -0,0 +1,6 @@
+#lang scribble/base
+
+@; Check that a macro-introduced `include-section' works:
+@(define-syntax-rule (inc) (include-section "diamond.scrbl"))
+
+@(inc)

pkgs/scribble-pkgs/scribble-test/tests/scribble/docs/include-section.txt

@@ -0,0 +1,7 @@
+1.
+
+This example checks that @ is not an escape character if we make a
+reader that uses a different escape character.
+
+It also makes sure that a non-ASCII character like diamond is ok as an
+escape character.