Minor update to if-else to avoid unnecessary query

If an anonymous learner visits the course tab view, we now perform one
less query to check enrollment status. This query has been moved inside
an else statement, and is only called if the learer is logged in.

lms/djangoapps/courseware/views/views.py

@@ -487,7 +487,6 @@ class CourseTabView(EdxFragmentView):
         """
         Register messages to be shown to the user if they have limited access.
         """
-        is_enrolled = CourseEnrollment.is_enrolled(request.user, course_key)
         if request.user.is_anonymous():
             PageLevelMessages.register_warning_message(
                 request,
@@ -502,23 +501,24 @@ class CourseTabView(EdxFragmentView):
                     ),
                 )
             )
-        elif not is_enrolled:
-            # Only show enroll button if course is open for enrollment.
-            if course_open_for_self_enrollment(course_key):
-                enroll_message = _('You must be enrolled in the course to see course content. \
-                        {enroll_link_start}Enroll now{enroll_link_end}.')
-                PageLevelMessages.register_warning_message(
-                    request,
-                    Text(enroll_message).format(
-                        enroll_link_start=HTML('<button class="enroll-btn btn-link">'),
-                        enroll_link_end=HTML('</button>')
+        else:
+            if not CourseEnrollment.is_enrolled(request.user, course_key):
+                # Only show enroll button if course is open for enrollment.
+                if course_open_for_self_enrollment(course_key):
+                    enroll_message = _('You must be enrolled in the course to see course content. \
+                            {enroll_link_start}Enroll now{enroll_link_end}.')
+                    PageLevelMessages.register_warning_message(
+                        request,
+                        Text(enroll_message).format(
+                            enroll_link_start=HTML('<button class="enroll-btn btn-link">'),
+                            enroll_link_end=HTML('</button>')
+                        )
+                    )
+                else:
+                    PageLevelMessages.register_warning_message(
+                        request,
+                        Text(_('You must be enrolled in the course to see course content.'))
                     )
-                )
-            else:
-                PageLevelMessages.register_warning_message(
-                    request,
-                    Text(_('You must be enrolled in the course to see course content.'))
-                )
 
     @staticmethod
     def handle_exceptions(request, course, exception):