Fix all modulestore calls to pass in user ids.

lms/djangoapps/instructor_task/tests/test_integration.py

@@ -105,6 +105,9 @@ class TestRescoringTask(TestIntegrationTask):
         self.create_student('u4')
         self.logout()
 
+        # set up test user for performing test operations
+        self.setup_user()
+
     def render_problem(self, username, problem_url_name):
         """
         Use ajax interface to request html for a problem.
@@ -294,7 +297,7 @@ class TestRescoringTask(TestIntegrationTask):
                 InstructorTaskModuleTestCase.problem_location(problem_url_name)
             )
             descriptor.data = problem_xml
-            self.module_store.update_item(descriptor, '**replace_user**')
+            self.module_store.update_item(descriptor, self.user.id)
         else:
             # Use "per-student" rerandomization so that check-problem can be called more than once.
             # Using "always" means we cannot check a problem twice, but we want to call once to get the