Fix the checks in the migration script, and fix a mistaken tweak in the new graded_count field

apps/openassessment/assessment/migrations/0004_auto__add_field_peerworkflow_graded_count.py

@@ -15,9 +15,9 @@ class Migration(SchemaMigration):
 
         if not db.dry_run:
             for workflow in orm.PeerWorkflow.objects.all():
-                graded_by = workflow.graded_by.all().order_by('id')
+                graded_by = workflow.graded_by.filter(assessment__isnull=False).order_by('assessment')
                 if graded_by:
-                    workflow.graded_count = workflow.graded_by.filter(assessment__null=False).count()
+                    workflow.graded_count = workflow.graded_by.filter(assessment__isnull=False).count()
                     workflow.save()
 
     def backwards(self, orm):

apps/openassessment/assessment/peer_api.py

@@ -910,7 +910,8 @@ def _close_active_assessment(workflow, submission_uuid, assessment):
     try:
         item = workflow.graded.get(submission_uuid=submission_uuid)
         item.assessment = assessment
-        item.scorer.graded_count += 1
+        item.author.graded_count += 1
+        item.author.save()
         item.save()
     except (DatabaseError, PeerWorkflowItem.DoesNotExist):
         error_message = _(