title: Jinja2 round filter not rounding
body: <p>I have the following code in my template:</p>
  
  <pre><code>data: [{% for deet in deets %} {{ deet.value*100|round(1) }}{% if not loop.last %},{% endif %} {% endfor %}]
  </code></pre>
  
  <p>I am expecting data rounded to 1 decimal place.  However, when I view the page or source, this is the output I'm getting:</p>
  
  <pre><code>data: [ 44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818 ]
  </code></pre>
  
  <p>This is not rounded to 1 decimal place.  It runs without a template error or anything, but produces incorrect output. My understanding <a href="http://jinja.pocoo.org/docs/templates/#round" rel="noreferrer">from the documentation</a>, and even <a href="https://stackoverflow.com/questions/7675653/rounding-in-jinja2-brackets">a related stack overflow question</a>, are that my format should work.  What am I missing or doing wrong?</p>