Markdown reader: fix interaction of --strip-comments and list

parsing.  Use of `--strip-comments` was causing tight lists
to be rendered as loose (as if the comment were a blank line).
Closes #7521.

src/Text/Pandoc/Readers/Markdown.hs

@@ -829,7 +829,7 @@ listLineCommon :: PandocMonad m => MarkdownParser m Text
 listLineCommon = T.concat <$> manyTill
               (  many1Char (satisfy $ \c -> c `notElem` ['\n', '<', '`'])
              <|> fmap snd (withRaw code)
-             <|> fmap snd (htmlTag isCommentTag)
+             <|> fmap (renderTags . (:[]) . fst) (htmlTag isCommentTag)
              <|> countChar 1 anyChar
               ) newline
 

test/command/7521.md

@@ -0,0 +1,11 @@
+```
+% pandoc  -- --strip-comments
+- one
+  <!-- with comm -->
+- two
+- ^D
+<ul>
+<li>one </li>
+<li>two</li>
+</ul>
+```