Fatal error when branch is not found

[jhbertra]

command (from a pure nix-shell): niv update nixpkgs -o NixOS -r nixpkgs-channels -b master

Here is the error dump I was shown:

Update nixpkgs
  FATAL: Could not read the output of 'nix-prefetch-url'. This is a bug. Please create a
  ticket:

    https://github.com/nmattia/niv/issues/new

  Thanks! I'll buy you a beer.
  command:
  nix-prefetch-url--unpack https://github.com/NixOS/nixpkgs/archive/nixpkgs-channels.tar.gz --name nixpkgs-channels.tar.gz
  stdout:

  stderr:
  error: unable to download 'https://github.com/NixOS/nixpkgs/archive/nixpkgs-channels.tar.gz': HTTP error 404

  FATAL: One or more packages failed to update:
  nixpkgs: ExitFailure 1
ERROR: ExitFailure 1

You can send me my beer in the mail 🍺

[nmattia]

Ah, looks like there's no master branch. Arguably niv could exit with a nicer error. You get a beer :)