Must use class attribute to get the selection values

Missing self to class migration during the AR migration

issue3478
review1591002
(transplanted from d9ed3eaf3396266f9586d8ff25ed6cdbef1660b3)

--HG--
extra : transplant_source : %D9%ED%3E%AF3%96%26o%95%86%D8%FF%25%EDl%DB%EF%16%60%B3