Some more optimizations

templates/problem/search-form.html

@@ -59,7 +59,7 @@
         <select id="search-author" name="authors" multiple>
           {% for author in all_authors %}
             <option value="{{ author.id }}"{% if author.id in author_query %} selected{% endif %}>
-              {{ author.user.username }}
+              {{ author.user__username }}
             </option>
           {% endfor %}
         </select>