pg_dump is broken by recent privileges changes

In CVS tip, create an empty database. pg_dump it. Try to restore the
dump. The first thing it does is

REVOKE ALL ON SCHEMA public FROM PUBLIC;

which fails with

ERROR: dependent privileges exist (use CASCADE to revoke them too)

This message seems incorrect --- what is a dependent privilege, and
why would PUBLIC have any? All I see in pg_namespace is

public | 1 | {=UC/postgres}

Also, pg_dump itself seems confused --- the full text of a dump from
an empty DB is (omitting comment lines)

\connect - postgres
REVOKE ALL ON SCHEMA public FROM PUBLIC;
GRANT ALL ON SCHEMA public TO PUBLIC;
GRANT ALL ON SCHEMA public TO PUBLIC;
REVOKE ALL ON SCHEMA public FROM postgres;

which is not only inefficient but wrong, since public surely should
have privileges when the dust settles.

regards, tom lane