django 1.6 fix for #191 - ArticleRevision.get_latest_by should be single field, not tuple

wiki/models/article.py

@@ -311,7 +311,7 @@ class ArticleRevision(BaseRevisionMixin, models.Model):
     
     class Meta:
         app_label = settings.APP_LABEL
-        get_latest_by = ('revision_number',)
+        get_latest_by = 'revision_number'
         ordering = ('created',)
         unique_together = ('article', 'revision_number')