There is a bug in python-lockfile available from jessie-backports: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=858835
This affects fresh installs of LAVA when LAVA is installed directly from jessie-backports without first being installed in jessie.
The underlying problem is with apt which pulls in the updated version of packages which have a backport available even if the requested package does not explicitly ask for the backport of that package.
The problem shows up with lava-coordinator first - the package fails to install cleanly because the daemon cannot be started correctly.
To fix this problem, simply instruct apt to install python-lockfile from jessie, not from jessie-backports:
apt install python-lockfile=1:0.8-2
lava-coordinator will then install correctly.
This change will persist over later upgrades as apt does not consider jessie-backports as upgrades of jessie - except in the case where the package is not yet installed.
Other daemons also now need to be restarted:
$ sudo service lava-server restart $ sudo service lava-master restart $ sudo service lava-slave restart
Future builds for the staging-repo and production-repo will force only version 1:0.8-2 of python-lockfile as these builds are done on and for jessie.
Systems already running Stretch or unstable do not seem to be affected and can safely use python-lockfile at version 1:0.12.2-2 - this is a particular problem inside jessie-backports. However, this does mean that until this bug is fixed, users running Stretch or unstable should build their own developer packages instead of using the LAVA repositories on images.validation.linaro.org. We currently do not have capacity to build separate packages for jessie and stretch.
(LAVA does not recommend using Stretch or unstable for production systems until Stretch has been released and stretch-backports becomes available.)