Fix bug when marking batch as executed.

Not sure why that ever worked, actually?

tailbone/views/batch.py

@@ -700,7 +700,7 @@ class BatchCrud(BaseCrud):
         else:
             if result:
                 batch.executed = datetime.datetime.utcnow()
-                batch.executed_by = self.request.user
+                batch.executed_by = session.merge(self.request.user)
                 session.commit()
             else:
                 session.rollback()