[Merge] ~osomon/software-properties:updates-refresh into software-properties:ubuntu/master

[Olivier Tilloy]

I've been playing with this and there doesn't appear to be a clean and reliable way to programatically fix a broken sources.list: force-enabling the release pocket will enable it for certain components (main and restricted I think), but we might still end up in an inconsistent state where another pocket has other components enabled.

The backend code however tells us when there's an inconsistent state, so I would suggest making the combobox insensitive in such cases. This wouldn't allow users to automagically fix their broken sources, but at least it wouldn't give them the wrong impression that they can change their update subscriptions.

What do you think?
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https://code.launchpad.net/~osomon/software-properties/+git/software-properties/+merge/379345
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