[Merge] lp:~rbalint/update-manager/fix-stale-pkg-refs into lp:update-manager

[Julian Andres Klode]

So, does this work reliably if a package disappears between stages? I'm not sure it can even haooen.
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https://code.launchpad.net/~rbalint/update-manager/fix-stale-pkg-refs/+merge/347195
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~rbalint/update-manager/fix-stale-pkg-refs into lp:update-manager.