drop the "/nix/store". I.e. instead of
http://hydra.nixos.org/jobset/nixpkgs/trunk/channel/latest/nar/nix/store/99djmii6l4yw9gn07zxqabh8z58pp84c-libmspack-0.0.20040308alpha.drv
we now have
http://hydra.nixos.org/nar/99djmii6l4yw9gn07zxqabh8z58pp84c-libmspack-0.0.20040308alpha.drv
The main reason is that this is much faster, since we don't need to
get all the channel data (which isn't used anyway for NAR
generation). This speeds up downloading a NAR from the Nixpkgs
channel by > 2 seconds.
* Drop "Hydra::View::" from view names to get rid of an ugly warning.