docbow: username should return user.username when first_name and last_name are both empty

fix bug introduced in f25be11

docbow_project/docbow/models.py

@@ -139,8 +139,9 @@ class Content(Model):
 
 def username(user):
     '''Return the full name of a user if it has one, the username otherwise.'''
-    full_name = u'{last_name} {first_name}'.format(**user.__dict__)
-    return full_name or user.username
+    if user.first_name or user.last_name:
+        return u'{last_name} {first_name}'.format(**user.__dict__)
+    return user.username
 
 
 def all_emails(user):

docbow_project/docbow/tests.py

@@ -137,6 +137,8 @@ class UtilsTestCase(BaseTestCase):
                 list(models.Document.objects.all())
 
         def test_document_accessors(self):
+            import pdb
+            pdb.set_trace()
             document = self.documents[0]
             self.assertEqual(document.filenames(),
                     'file0.pdf, file1.pdf')