Erroneous HTML added

Note: only happens when the shortcode is contained within nested divs, like this:

<div class="frp-left">
	<div class="calendar-date">
		<div class="calendar-month">[frp_date format="M" time_since="0"]</div>
		<div class="calendar-day">[frp_date format="j" time_since="0"]</div>
	</div>
</div>

The problem is in function wpautop(). Just try to create new Text widget, insert the same contents and put a tick to “Automatically add paragraphs” checkbox. You would see the same result.
That function is very buggy as for me. Try to remove all whitespaces and the problem will be solved:

<div class=”frp-left”><div class=”calendar-date”><div class=”calendar-month”>[frp_date format=”M” time_since=”0″]</div><div class=”calendar-day”>[frp_date format=”j” time_since=”0″]</div></div></div>