[Merge] lp:~xnox/upstart/bug-1199778 into lp:upstart

[Dmitrijs Ledkovs]

The 1-to-1 mapping would have worked, if json_job_classes were sorted by session_id, but they were not. So we now have to account for that.
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https://code.launchpad.net/~xnox/upstart/bug-1199778/+merge/174372
Your team Upstart Reviewers is requested to review the proposed merge of lp:~xnox/upstart/bug-1199778 into lp:upstart.