function format doesn't support values with variadic flag

Hello

this code should to work, but it doesn't

postgres=# select format('%s %s', variadic array['Hello','World']);
ERROR: too few arguments for format

postgres=# create or replace function un(variadic integer[])
postgres-# returns setof int as $$ select unnest($1)$$ language sql;
CREATE FUNCTION
postgres=# select un(1,2,3,4);
un
────
1
2
3
4
(4 rows)

postgres=# select un(variadic array[1,2,3]);
un
────
1
2
3
(3 rows)

A problem is in too simple evaluation of "any" parameter - without
check to "VARIADIC" flag

Regards

Pavel Stehule