[Nix-dev] nix-channel --update failing for nixos-unstable

[Michael Alan Dorman]

I suspect this is somehow self-inflicted, but I was hoping for some
guidance in resolving it.  Here's what happens:

-bash-4.3# nix-channel --update
downloading Nix expressions from
‘https://nixos.org/releases/nixos/unstable/nixos-15.05pre61665.4c01e6d/nixexprs.tar.xz’...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time 
  Current
                                 Dload  Upload   Total   Spent    Left 
                                 Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
      0
unpacking channels...
/nix/store/j7ghngyylfkl64xx1js6f2dfix48fw7g-xz-5.2.0/bin/xz: (stdin):
File format not recognized
/nix/store/s16y2pk8lljsm37b55h2dsl6gpbsb62g-gnutar-1.27.1/bin/tar: This
does not look like a tar archive
/nix/store/s16y2pk8lljsm37b55h2dsl6gpbsb62g-gnutar-1.27.1/bin/tar:
Exiting with failure status due to previous errors
builder for
‘/nix/store/pbx0r34miwhvabz1zd41wfyyp72gkbbi-nixos-unstable-15.05pre61665.4c01e6d.drv’
failed with exit code 2
error: build of
‘/nix/store/pbx0r34miwhvabz1zd41wfyyp72gkbbi-nixos-unstable-15.05pre61665.4c01e6d.drv’
failed
cannot unpack the channels at /run/current-system/sw/bin/nix-channel
line 150.