Minor adding c_id in query

main/coursecopy/classes/CourseBuilder.class.php

@@ -510,6 +510,7 @@ class CourseBuilder {
                 LEFT JOIN $table_qui as exercices
                     ON (exercice_id = exercices.id AND exercices.c_id = $course_id AND questions.c_id = $course_id)
                 WHERE  questions.c_id = $course_id AND
+                       exercices.c_id = $course_id AND
                        (quizz_questions.exercice_id IS NULL OR exercices.active = -1) "; // active = -1 means "deleted" test.
 
         $db_result = Database::query($sql);