http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=802677

This appears to only affect the unit tests in lava-server but can be confusing as the output makes it look like something more serious within django. It's not, it's in python-testtools.

The solution is to downgrade python-testtools (use the version in Jessie as outlined in the bug report above).

When this bug report is closed, the package can be upgraded again.