fix nim-lang#14485 ; workaround for strutils.addf bug

compiler/renderverbatim.nim

@@ -65,10 +65,26 @@ proc renderNimCode*(result: var string, code: string, isLatex = false) =
     buf.setLen 0
     buf.addEscaped(val)
     let class = tokenClassToStr[kind]
+
+    #[
+    xxx bug in strutils.addf: this crashes:
+    var ret: string
+    ret.addf "foo $1 bar" % ["$"]
+    ]#
+    when false:
+      if isLatex:
+        result.addf "\\span$1{$2}" % [class, buf]
+      else:
+        result.addf  "<span class=\"$1\">$2</span>" % [class, buf]
+
     if isLatex:
-      result.addf "\\span$1{$2}" % [class, buf]
+      result.addf "\\span$1{" % [class]
+       result.add buf
+       result.add "}"
     else:
-      result.addf  "<span class=\"$1\">$2</span>" % [class, buf]
+      result.addf  "<span class=\"$1\">" % [class]
+      result.add buf
+      result.add buf "</span>"
 
   while true:
     getNextToken(toknizr, langNim)