renameatt() can rename attribute of index, sequence, ...

Is it an expected behavior?

postgres=> CREATE SEQUENCE s;
CREATE SEQUENCE
postgres=> ALTER TABLE s RENAME sequence_name TO abcd;
ALTER TABLE

postgres=> CREATE TABLE t (a int primary key, b text);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "t_pkey" for table "t"
CREATE TABLE
postgres=> ALTER TABLE t_pkey RENAME a TO xyz;
ALTER TABLE

The documentation says:
http://developer.postgresql.org/pgdocs/postgres/sql-altertable.html

:
RENAME
The RENAME forms change the name of a table (or an index, sequence, or view) or
the name of an individual column in a table. There is no effect on the stored data.

It seems to me the renameatt() should check relkind of the specified relation, and
raise an error if relkind != RELKIND_RELATION.

--
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>