[Merge] lp:~sil2100/update-manager/fix-test-failure-origin into lp:update-manager

[Łukasz Zemczak]

This change fixes the current artful autopkgtest failure which started happening when we released a new packagekit SRU to xenial-updates.

https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-artful/artful/armhf/u/update-manager/20170907_003254_8b9e0@/log.gz
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https://code.launchpad.net/~sil2100/update-manager/fix-test-failure-origin/+merge/330446
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~sil2100/update-manager/fix-test-failure-origin into lp:update-manager.