+ --
+ -- #4072: note that we must retain the ordering of the list here
+ -- so that shadowing behaves as expected when we apply it later.
+ pkgs0_unique = snd $ foldr del (Set.empty,[]) pkgs0
+ where del p (s,ps)
+ | pid `Set.member` s = (s,ps)
+ | otherwise = (Set.insert pid s, p:ps)
+ where pid = installedPackageId p
+ -- XXX this is just a variant of nub
+
+ ipid_map = Map.fromList [ (installedPackageId p, p) | p <- pkgs0 ]