The comment code refactoring c10575ff005c330d0475345621b7d381eb510c48
broke comments on composite type attributes:
COMMENT ON COLUMN foo.a is 'test';
ERROR: 42809: "foo" is a composite type
LOCATION: heap_openrv, heapam.c:1110
This is because as the code was moved from CommentAttribute() to
get_object_address_attribute(), the call to relation_openrv() became a
heap_openrv(), which causes the above error.
Please check it out.