Use CourseOverview instead of modulestore.

lms/djangoapps/certificates/signals.py

@@ -6,7 +6,8 @@ from django.dispatch.dispatcher import receiver
 
 from certificates.models import CertificateGenerationCourseSetting
 from opaque_keys.edx.keys import CourseKey
-from xmodule.modulestore.django import SignalHandler, modulestore
+from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
+from xmodule.modulestore.django import SignalHandler
 
 
 @receiver(SignalHandler.course_published)
@@ -22,7 +23,7 @@ def _listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable
 def enable_self_generated_certs(course_key):
     """Enable the self-generated certificates by default for self-paced courses."""
     course_key = CourseKey.from_string(course_key)
-    course = modulestore().get_course(course_key)
+    course = CourseOverview.get_from_id(course_key)
     is_enabled_for_course = CertificateGenerationCourseSetting.is_enabled_for_course(course_key)
     if course.self_paced and not is_enabled_for_course:
         CertificateGenerationCourseSetting.set_enabled_for_course(course_key, True)