simpify process_survey_link

common/djangoapps/student/views.py

@@ -133,11 +133,7 @@ def process_survey_link(survey_link, user):
     If {UNIQUE_ID} appears in the link, replace it with a unique id for the user.
     Currently, this is sha1(user.username).  Otherwise, return survey_link.
     """
-    to_replace = '{UNIQUE_ID}'
-    if to_replace in survey_link:
-        return survey_link.replace(to_replace, unique_id_for_user(user))
-
-    return survey_link
+    return survey_link.format(UNIQUE_ID=unique_id_for_user(user))
 
 
 def cert_info(user, course):