title: elisp libxml-parse-html-region return NIL
body: <pre><code>Here my elisp code (test by url "http://httpbin.org/html")
  
     (with-current-buffer (url-retrieve-synchronously my-url)
      (goto-char (point-min))
      (re-search-forward "^$")
      (delete-region (point) (point-min))
      (setq dom (libxml-parse-html-region (point-min) (point-max)))
      (hoge--log-trace "Current buffer content: %s" (buffer-string))
      (hoge--log-trace "DOM is: %s" dom)
      )
  
  To parse html I use elisp function "libxml-parse-html-region"
  
  The result is:
  
  Current buffer content: 
  &lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
    &lt;/head&gt;
    &lt;body&gt;
        &lt;h1&gt;Herman Melville - Moby-Dick&lt;/h1&gt;
  
        &lt;div&gt;
          &lt;p&gt;
            Availing himself ...
          &lt;/p&gt;
        &lt;/div&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  DOM is: nil
  </code></pre>
  
  <p>As you can see the buffer has content, but elisp function <strong>libxml-parse-html-region</strong> return nill and as result DOM object is NIL. Why?</p>