[Merge] ~renanrodrigo/update-notifier:respect-phasing into update-notifier:master

[Athos Ribeiro]

Thanks, Renan!

I added some inline comments/questions.

Also, would you mind linking a PPA containing builds for this package with the proposed changes?
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https://code.launchpad.net/~renanrodrigo/update-notifier/+git/update-notifier/+merge/438009
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