HTML writer: fix bug with --number-offset.

This formerly caused section divs to be produced, even
when `--section-divs` was not specified.  Closes #8097.

src/Text/Pandoc/Writers/HTML.hs

@@ -743,6 +743,8 @@ adjustNumbers opts doc =
      then doc
      else walk go doc
   where
+   go (Div (ident,"section":classes,kvs) lst) =
+     Div (ident,"section":classes,map fixnum kvs) lst
    go (Header level (ident,classes,kvs) lst) =
      Header level (ident,classes,map fixnum kvs) lst
    go x = x

test/command/8097.md

@@ -0,0 +1,9 @@
+```
+% pandoc --number-sec --number-offset=2 --wrap=none
+# One
+
+# two
+^D
+<h1 data-number="3" id="one"><span class="header-section-number">3</span> One</h1>
+<h1 data-number="4" id="two"><span class="header-section-number">4</span> two</h1>
+```