Comment 4 for bug 1604750

Same problem with aptitude full-upgrade on Linux Mint.

uname -a
Linux server 4.4.0-45-generic #66-Ubuntu SMP Wed Oct 19 14:12:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

byobu -v
byobu version 5.106
tmux 2.1

 bash --version
GNU bash, version 4.3.42(1)-release (x86_64-pc-linux-gnu)

cat /etc/*release*
DISTRIB_ID=LinuxMint
DISTRIB_RELEASE=18
DISTRIB_CODENAME=sarah
DISTRIB_DESCRIPTION="Linux Mint 18 Sarah"
DISTRIB_ID=LinuxMint
DISTRIB_RELEASE=17.3
DISTRIB_CODENAME=rosa
DISTRIB_DESCRIPTION="Linux Mint 17.3 Rosa"
NAME="Linux Mint"
VERSION="18 (Sarah)"
ID=linuxmint
ID_LIKE=ubuntu
PRETTY_NAME="Linux Mint 18"
VERSION_ID="18"
HOME_URL="http://www.linuxmint.com/"
SUPPORT_URL="http://forums.linuxmint.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/linuxmint/"
UBUNTU_CODENAME=xenial
cat: /etc/upstream-release: Is a directory