[Merge] lp:~jamesodhunt/upstart/cgroups-and-process_data-reexec-test into lp:upstart

[James Hunt]

What was there was fine, but the test changes were missing explicit checks on JobProcessData "post re-exec".

Adding those tests identified a problem which would otherwise have laid dormant: we weren't serialising JobProcessData->status.
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https://code.launchpad.net/~jamesodhunt/upstart/cgroups-and-process_data-reexec-test/+merge/225360
Your team Upstart Reviewers is requested to review the proposed merge of lp:~jamesodhunt/upstart/cgroups-and-process_data-reexec-test into lp:upstart.