Tpl: Incorrect indentation for multi-line self closing tags

[jdufresne]

Take the following template:

{% if context_var %}
  <img class="my-class"
       src="blah.png"
       alt="an image">
{% endif %}

Upon indenting the entire buffer, the result then looks like:

{% if context_var %}
  <img class="my-class"
       src="blah.png"
       alt="an image">
     {% endif %}

I would expect it to remain the same. This only happens when the self closing tag spans multiple lines. This happens for both XHTML style self closing tags (<img />) and HTML5 style self closing tags (<img>).