guix package -i hello
accepted connection from pid 16464, uid 1000
The following package will be installed:
   hello-2.8 out /nix/store/7g06kqdm6qjbzdppnryyvjl2bz82r8dh-hello-2.8

The following files will be downloaded:
   /nix/store/7g06kqdm6qjbzdppnryyvjl2bz82r8dh-hello-2.8
   /nix/store/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3
@ substituter-started /nix/store/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3
/usr/local/libexec/guix/substitute-binary
downloading `/nix/store/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3' from `
http://hydra.gnu.org/nar/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3'...
bzip2: (stdin) is not a bzip2 file.
Backtrace:
In ice-9/boot-9.scm:
 157: 11 [catch #t #<catch-closure 23b3d40> ...]
In unknown file:
   ?: 10 [apply-smob/1 #<catch-closure 23b3d40>]
In ice-9/boot-9.scm:
  63: 9 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
 432: 8 [eval # #]
In ice-9/boot-9.scm:
2320: 7 [save-module-excursion #<procedure 23e1cc0 at
ice-9/boot-9.scm:3961:3 ()>]
3966: 6 [#<procedure 23e1cc0 at ice-9/boot-9.scm:3961:3 ()>]
In unknown file:
   ?: 5 [load-compiled/vm
"/root/.cache/guile/ccache/2.0-LE-8-2.0/usr/local/bin/guix.go"]
In guix/ui.scm:
 445: 4 [run-guix-command substitute-binary "--substitute" ...]
In guix/scripts/substitute-binary.scm:
 439: 3 [guix-substitute-binary "--substitute" ...]
In guix/nar.scm:
 177: 2 [restore-file #<input: #{read pipe}# 6> ...]
In guix/serialization.scm:
  77: 1 [read-string #<input: #{read pipe}# 6>]
  49: 0 [read-int #<input: #{read pipe}# 6>]

guix/serialization.scm:49:4: In procedure read-int:
guix/serialization.scm:49:4: In procedure bv-u32-ref: Wrong type argument
in position 1 (expecting bytevector): #<eof>
@ substituter-failed /nix/store/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3
256 fetching path `/nix/store/gk8dpqzml7n6ah0nxi59hrpwjaqqml64-gcc-4.7.3'
failed with exit code 1
guix package: error: build failed: some substitutes for the outputs of
derivation `/nix/store/bc6hgclkr7a3yq3xh7h6m7myagfdwvdj-hello-2.8.drv'
failed; try `--fallback'
249 operations

On arch x86_64, with guile 2.0.9, with localstatedir set to /usr/local/var

Thanks!
[Chris] Dale