Do not recurse on auto_id adding if header didn't change (#15)

* only recurse if attr changed
* regression test

Author: cscheid

crates/quarto_markdown_pandoc/src/pandoc/treesitter.rs

@@ -1820,8 +1820,12 @@ fn desugar(doc: Pandoc) -> Result<Pandoc, Vec<String>> {
                     let mut attr = header.attr.clone();
                     if attr.0.is_empty() {
                         attr.0 = autoid::auto_generated_id(&header.content);
-                        header.attr = attr;
-                        FilterResult(vec![Block::Header(header)], true)
+                        if !is_empty_attr(&attr) {
+                            header.attr = attr;
+                            FilterResult(vec![Block::Header(header)], true)
+                        } else {
+                            Unchanged(header)
+                        }
                     } else {
                         Unchanged(header)
                     }

crates/quarto_markdown_pandoc/tests/smoke/018.qmd

@@ -0,0 +1,3 @@
+# $any$
+
+https://github.com/quarto-dev/quarto-markdown/issues/14