Add __unicode__ method on StudentModuleHistory

lms/djangoapps/courseware/models.py

@@ -185,6 +185,9 @@ class StudentModuleHistory(models.Model):
                                                  max_grade=instance.max_grade)
             history_entry.save()
 
+    def __unicode__(self):
+        return unicode(repr(self))
+
 
 class XBlockFieldBase(models.Model):
     """