`content-with-more-marker` returns a HTML string when the `content`
conteins more marker ("<!--more-->").
In many case, HTML tags in `content` is balanced.
ex.
------------------------------
<div id='post'>
<div class='post-content'>
this post has more marker
<!--more-->
and more content.
</div>
</div>
------------------------------
But original code breaks the balance.
------------------------------
<div id='post'>
<div class='post-content'>
this post has more marker
------------------------------
Afer this patch applied, `tagsoup` read above text and `hiccup`
re-render to HTML text with correct balanced tags.
------------------------------
<div id='post'>
<div class='post-content'>
this post has more marker
</div></div>
------------------------------
