jenkins@cyclops-node19:~$ schroot -c xenial-armhf -d / -u root 
(xenial-armhf)root@cyclops-node19:/# apt-get update
Get:1 http://ports.ubuntu.com/ubuntu-ports xenial InRelease [247 kB]
Get:2 http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease [82.2 kB]
Get:3 http://ports.ubuntu.com/ubuntu-ports xenial-proposed InRelease [247 kB]
Ign:1 http://ports.ubuntu.com/ubuntu-ports xenial InRelease  
Ign:2 http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease
Get:4 http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease [82.2 kB]
Get:5 http://ports.ubuntu.com/ubuntu-ports xenial/main Sources [865 kB]
Ign:3 http://ports.ubuntu.com/ubuntu-ports xenial-proposed InRelease
Ign:4 http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease
Get:6 http://ports.ubuntu.com/ubuntu-ports xenial/universe Sources [7757 kB]
Get:7 http://ports.ubuntu.com/ubuntu-ports xenial/main armhf Packages [1146 kB]
Get:8 http://ports.ubuntu.com/ubuntu-ports xenial/universe armhf Packages [7319 kB]
Get:9 http://ports.ubuntu.com/ubuntu-ports xenial/universe Translation-en [4360 kB]
Get:10 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/main Sources [11.0 kB]
Get:11 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/universe Sources [72.3 kB]
Get:12 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/main armhf Packages [12.3 kB]
Get:13 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/main Translation-en [10.0 kB]
Get:14 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/universe armhf Packages [79.0 kB]
Get:15 http://ports.ubuntu.com/ubuntu-ports xenial-proposed/universe Translation-en [52.7 kB]
Fetched 22.3 MB in 14s (1510 kB/s)                                             
Reading package lists... Done
W: No sandbox user '_apt' on the system, can not drop privileges
W: GPG error: http://ports.ubuntu.com/ubuntu-ports xenial InRelease: Could not execute 'apt-key' to verify signature (is gnupg installed?)
W: The repository 'http://ports.ubuntu.com/ubuntu-ports xenial InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease: Could not execute 'apt-key' to verify signature (is gnupg installed?)
W: The repository 'http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports xenial-proposed InRelease: Could not execute 'apt-key' to verify signature (is gnupg installed?)
W: The repository 'http://ports.ubuntu.com/ubuntu-ports xenial-proposed InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease: Could not execute 'apt-key' to verify signature (is gnupg installed?)
W: The repository 'http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.