[Q21.5] Return a list copy in #'built-in-face-specifiers, pre-empting modification.

[Aidan Kehoe]

 Ar an dara lá is fiche de mí na Nollaig, scríobh Stephen J. Turnbull: 

 > QUERY
 > 
 > Aidan Kehoe writes:
 >  > 
 >  > Small change, prevention is a better mechanism than admonishment. 
 > 
 > Please fix the docstring to indicate that modifying the list will have
 > no effect on any faces.

Done, though not phrased exactly like that. 

-- 
¿Dónde estará ahora mi sobrino Yoghurtu Nghé, que tuvo que huir
precipitadamente de la aldea por culpa de la escasez de rinocerontes?