User-agent:
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0
The exact same job (packaging: lp:~maas-maintainers/maas/packaging,
upstream: lp:maas, tests: lp:~maas-maintainers/maas/qa-lab-tests) passes
on Trusty [0] so the problem is likely to be caused by a dependency or
by an interaction between MAAS and a dependency (on Utopic).