WYSIWIG integration results in broken paragraphs

WYSIWYG editors like to wrap everything in paragraph tags, so a common scenario is this:

<p>My first paragraph.</p>
<p>[caption]<img src="" alt="" />This is an image caption[/caption] My second paragraph.</p>
<p>My third paragraph.</p>

Caption Filter borks replacement of the caption:

<p>My first paragraph.</p>
<div class="caption-inner">
  <img alt="" src="" />
  This is an image caption
</div>
My second paragraph.</p>
<p>My third paragraph.</p>

Note the missing opening p tag for the second paragraph. The problem lies in Drupal.captionFilter.toHTML(). The regex includes the opening paragraph tag in co.replace(), but doesn't include it in the replacement.