pre block-level tag shouldn't be surrounded by a p tag

If we write this:

Voici le code:

<pre>
$a = 5;

$b = 6;

$c = 7;
</pre>

Nous y voyons les valeurs des variables.

Markdown filter adds p tags around pre tag and inside, so presently the module outputs this:

<p>Voici le code:</p>

<p><pre>
$a = 5;</p>

<p>$b = 6;</p>

<p>$c = 7;
</pre></p>

<p>Nous y voyons les valeurs des variables.</p>

but it's a mistake. According to the Markdown documentation:

The only restrictions are that block-level HTML elements — e.g. <div>, <table>, <pre>, <p>, etc. — must be separated from surrounding content by blank lines, and the start and end tags of the block should not be indented with tabs or spaces. Markdown is smart enough not to add extra (unwanted)

tags around HTML block-level tags.

We can also test it here: http://michelf.com/projets/php-markdown/banc-d%27essai/

So the good output should be:

<p>Voici le code:</p>

<pre>
$a = 5;

$b = 6;

$c = 7;
</pre>

<p>Nous y voyons les valeurs des variables.</p>