Hi guix,

The tests 'tests/substitute.scm' and 'tests/containers.scm' failed, the
relevant logs are attched below.

The machine has the following 'uname -a' output:
  Linux debian 4.6.0-1-amd64 #1 SMP Debian 4.6.1-1 (2016-06-06) x86_64 GNU/Linux

Thanks,
Alex