is done by instantiating a webserver that simulates nixos.org.
Using nix-push we create a channel that contains some stuff (namely
the GNU Hello source tarball and the rlwrap program). This was a
bit tricky because nix-push requires a writable Nix store. Using
AUFS this is possible, but not on recent Linux kernels (AUFS1 over
CIFS fails).
svn path=/nixos/trunk/; revision=19327