bulk_email fix course_image_unicode name

lms/djangoapps/bulk_email/tasks.py

+# -*- coding: utf-8 -*-
 """
 This module contains celery task functions for handling the sending of bulk email
 to a course.
@@ -152,7 +153,7 @@ def _get_course_email_context(course):
         settings.SITE_NAME,
         reverse('course_root', kwargs={'course_id': course_id})
     )
-    image_url = 'https://{}{}'.format(settings.SITE_NAME, course_image_url(course))
+    image_url = u'https://{}{}'.format(settings.SITE_NAME, course_image_url(course))
     email_context = {
         'course_title': course_title,
         'course_url': course_url,

lms/djangoapps/bulk_email/tests/test_tasks.py

+# -*- coding: utf-8 -*-
 """
 Unit tests for LMS instructor-initiated background tasks.
 
@@ -28,6 +29,8 @@ from celery.states import SUCCESS, FAILURE
 from django.conf import settings
 from django.core.management import call_command
 
+from xmodule.modulestore.tests.factories import CourseFactory
+
 from bulk_email.models import CourseEmail, Optout, SEND_TO_ALL
 
 from instructor_task.tasks import send_bulk_course_email
@@ -408,3 +411,15 @@ class TestBulkEmailInstructorTask(InstructorTaskCourseTestCase):
 
     def test_failure_on_ses_domain_not_confirmed(self):
         self._test_immediate_failure(SESDomainNotConfirmedError(403, "You're out of bounds!"))
+
+    def test_bulk_emails_with_unicode_course_image_name(self):
+        # Test bulk email with unicode characters in course image name
+        course_image = u'在淡水測試.jpg'
+        self.course = CourseFactory.create(course_image=course_image)
+
+        num_emails = 1
+        self._create_students(num_emails)
+
+        with patch('bulk_email.tasks.get_connection', autospec=True) as get_conn:
+            get_conn.return_value.send_messages.side_effect = cycle([None])
+            self._test_run_with_task(send_bulk_course_email, 'emailed', num_emails, num_emails)