This was missed when the feature was added.
  Reported-by: Vik Fearing Discussion: https://postgr.es/m/
eca20529-0b06-b493-ee38-
f071a75dcd5b@postgresfriends.org 
 Backpatch-through: 10  
 
                  COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_routines, NULL);
     else if (TailMatchesCS("\\sv*"))
         COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_views, NULL);
 -   else if (TailMatchesCS("\\cd|\\e|\\edit|\\g|\\i|\\include|"
 +   else if (TailMatchesCS("\\cd|\\e|\\edit|\\g|\\gx|\\i|\\include|"
                            "\\ir|\\include_relative|\\o|\\out|"
                            "\\s|\\w|\\write|\\lo_import"))
     {