title: Django custom assignment_tag does not get executed
body: <p>I try to make my own assignment template tag in Django 1.6 (edit: I also tried it with 1.5.5 w/o success) but I can't get it to do anything.</p>
  
  <p>In <code>templatetags/getattribute.py</code> I have:</p>
  
  <pre><code>from django import template
  import logging
  
  register = template.Library()
  logger = logging.getLogger('wwwcid.website.debug_console')
  
  #@register.assignment_tag
  def mytag(context, context_variable):
      raise template.TemplateSyntaxError("buuuuuuuuuuuuuuus")
      logger.debug("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
      print "teeeeeeeeeeeeeeeeeeeest"
      return 'tpppppppppppppppppppppeee'
  register.assignment_tag(mytag, takes_context=True)
  </code></pre>
  
  <p>In my template <code>profile.html</code> I have:</p>
  
  <pre><code>{% extends "website/base.html" %}
  {% load getattribute %}
  {% mytag "user.email" as vari %}
  {{ vari }}
  {% block content %}
  &lt;p&gt; Rest of the page. &lt;/p&gt;
  {% endblock content %}
  </code></pre>
  
  <p>But this tag does not work. No error is raised (even if I raise it myself), no logging output, no print, no return, nothing.</p>
  
  <p>Even if I register the tag w/o the takes_context=True, say just <code>@register.assignment_tag</code> it does not work. What am I doing wrong here? Thanks for your help!</p>