[Merge] lp:~mvo/ubuntu-release-upgrader/use-str.format into lp:ubuntu-release-upgrader

[Barry Warsaw]

Also note that with modern Pythons

'{0}'.format('foo')

is equivalent to

'{}'.format('foo')

-- 
https://code.launchpad.net/~mvo/ubuntu-release-upgrader/use-str.format/+merge/217004
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~mvo/ubuntu-release-upgrader/use-str.format into lp:ubuntu-release-upgrader.