Fix UnicodeError with anonymous student IDs

common/djangoapps/student/models.py

@@ -100,7 +100,7 @@ def anonymous_id_for_user(user, course_id, save=True):
     hasher.update(settings.SECRET_KEY)
     hasher.update(unicode(user.id))
     if course_id:
-        hasher.update(course_id.to_deprecated_string())
+        hasher.update(course_id.to_deprecated_string().encode('utf-8'))
     digest = hasher.hexdigest()
 
     if not hasattr(user, '_anonymous_id'):

common/djangoapps/student/tests/tests.py

+# -*- coding: utf-8 -*-
 """
 This file demonstrates writing tests using the unittest module. These will pass
 when you run "manage.py test".
@@ -736,3 +737,11 @@ class AnonymousLookupTable(TestCase):
         real_user = user_by_anonymous_id(anonymous_id)
         self.assertEqual(self.user, real_user)
         self.assertEqual(anonymous_id, anonymous_id_for_user(self.user, self.course.id, save=False))
+
+    def test_roundtrip_with_unicode_course_id(self):
+        course2 = CourseFactory.create(org=self.COURSE_ORG, display_name=u"Omega Course Ω", number=self.COURSE_SLUG)
+        CourseEnrollment.enroll(self.user, course2.id)
+        anonymous_id = anonymous_id_for_user(self.user, course2.id)
+        real_user = user_by_anonymous_id(anonymous_id)
+        self.assertEqual(self.user, real_user)
+        self.assertEqual(anonymous_id, anonymous_id_for_user(self.user, course2.id, save=False))