On modern Pg:
ALTER TABLE part_pkg DROP CONSTRAINT part_pkg_temp_pkey;
ALTER TABLE part_pkg ADD PRIMARY KEY (pkgpart);
-select setval('public.part_pkg_temp_pkgpart_seq', ( select max(pkgpart) from part_pkg) ); #?
+select setval('public.part_pkg_temp_pkgpart_seq', ( select max(pkgpart) from part_pkg) );
Or on Pg versions that don't support DROP CONSTRAINT and ADD PRIMARY KEY (tested on 7.1 so far):
DROP INDEX part_pkg_temp_pkey;