reason for wrapping an anchor in a form?

Question

This is one of those "found in someone else's code and wondering what they're thinking" questions...

The HTML being generated is of the form

<form method="post" action="#">
  <a href="?some&query&string&stuff">
    <img src="https://www.example.com/pictures/pict.gif" /></a>
</form>

The form has no other contents than the anchor and the image inside of it. Is there some reason to wrap an anchor in a form like that?

The only reason I can guess is to make it selectable in CSS, but it would seem the obvious solution for that is a <div class="my_anchor_wrapper">.

So I'm wondering if there's something magic about this construct that I'm missing.

Thanks for any HTMLightenment here.