Fix unused-import errors

common/djangoapps/student/tests/test_enrollment.py

@@ -13,7 +13,7 @@ from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
 from util.testing import UrlResetMixin
 from embargo.test_utils import restrict_course
-from student.tests.factories import UserFactory, CourseModeFactory, CourseEnrollmentFactory
+from student.tests.factories import UserFactory, CourseModeFactory
 from student.models import CourseEnrollment, CourseFullError
 from student.roles import (
     CourseInstructorRole,

common/djangoapps/student/tests/test_reset_password.py

@@ -13,8 +13,7 @@ from django.contrib.auth.models import User
 from django.contrib.auth.hashers import UNUSABLE_PASSWORD_PREFIX
 from django.contrib.auth.tokens import default_token_generator
 
-from django.utils.encoding import force_bytes, force_text
-from django.utils.http import urlsafe_base64_encode, base36_to_int, int_to_base36
+from django.utils.http import int_to_base36
 
 from mock import Mock, patch
 import ddt

common/djangoapps/student/tests/test_user_profile_properties.py

@@ -2,7 +2,6 @@
 
 import datetime
 import ddt
-from django.test import TestCase
 
 from student.models import UserProfile
 from student.tests.factories import UserFactory