[Merge] lp:~serge-hallyn/auto-upgrade-testing/uvtool into lp:auto-upgrade-testing

[Serge Hallyn]

I've addressed some feedback from rharper and pushed the result.

I still need to implement the snapshotting, then I believe it will be at feature parity.
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https://code.launchpad.net/~serge-hallyn/auto-upgrade-testing/uvtool/+merge/207350
Your team Auto Upgrade Testing Developers is requested to review the proposed merge of lp:~serge-hallyn/auto-upgrade-testing/uvtool into lp:auto-upgrade-testing.