Commit ae68cad7 introduced a regression that
makes lxc-attach ignore the exit status of the executed command. This was first
identified in 3.0.4 LTS, while it worked on 3.0.3.

  # lxc-attach --version
  3.0.4
  # lxc-attach -n test false; echo $?
  0
Signed-off-by: Antonio Terceiro <terceiro@debian.org>
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=934983