Remove unicode conversion of email since it should always be unicode

lms/djangoapps/instructor_task/tasks_helper.py

@@ -547,7 +547,7 @@ def push_grades_to_s3(_xmodule_instance_args, _entry_id, course_id, _task_input,
             # possible for a student to have a 0.0 show up in their row but
             # still have 100% for the course.
             row_percents = [percents.get(label, 0.0) for label in header]
-            rows.append([student.id, unicode(student.email).encode('utf-8'), student.username, gradeset['percent']] + row_percents)
+            rows.append([student.id, student.email.encode('utf-8'), student.username, gradeset['percent']] + row_percents)
         else:
             # An empty gradeset means we failed to grade a student.
             num_failed += 1

lms/djangoapps/instructor_task/tests/test_tasks_helper.py

@@ -48,10 +48,8 @@ class TestInstructorGradeReport(TestCase):
         """
         Test that students with unicode characters in emails is handled.
         """
-        i = 0
-        for email in emails:
+        for i, email in enumerate(emails):
             self.create_student('student{0}'.format(i), email)
-            i += 1
 
         self.current_task = Mock()
         self.current_task.update_state = Mock()