The reason this is optional is because we might want to use it for bootstrapping
in some constellations. And we really don't want whole lot of dependencies in
those situations.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
URLs to http://nix.cs.uu.nl/dist/tarballs. With content-addressable
mirror support (r9190, NIXPKGS-70) this is no longer necessary:
fetchurl will try to download from that location automatically. So
we can keep the original URLs.
svn path=/nixpkgs/trunk/; revision=9192
