[Merge] ~nteodosio/software-properties:drivers-hang into software-properties:ubuntu/master

[Nathan Teodosio]

> Is it normal that I'm getting this cryptic error on cancellation: https://i.imgur.com/dQNByFJ.png

Yes, the cancellation of the sub-process is done by sending TERM = 15. I did not think it was worth the additional code but now I think you are right, I'll alter it to show nothing as there is already the retry button.

> From an UI prospective, I think the button should be centered in the parent frame and we should only have one button for Retry/Cancel that is shown only when it matters.

I dislike that approach because it creates click instability (a term that I just invented :)), meaning you never know what you are actually going to click if the button can suddenly change meaning between the decision to click it and the actual action of clicking it.
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https://code.launchpad.net/~nteodosio/software-properties/+git/software-properties/+merge/470812
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~nteodosio/software-properties:drivers-hang into software-properties:ubuntu/master.