title: Django reverse url with optional arguments in template
body: <p>In my django project I have a simple url</p>
  
  <pre><code>url(r'^report/(?P&lt;slug&gt;[\w-]+)/$', views.Report.as_view(), name='report')
  </code></pre>
  
  <p>I have placed this particular url at the bottom of my url file for the app. The slug field is an optional argument which may or may not be supplied as part of request.</p>
  
  <p>Now, in a template when I refer to this url with this syntax <code>{% url 'appname:report' %}</code> I get an NoReverseMatch found error. I have tried same thing in another app and it works fine. Can anyone point out the probable cause for such behavior? I know I can have two separate urls but if it can be done using one, I would prefer it.</p>