[Merge] ~callmepk/ubuntu-release-upgrader:ubuntu/master into ubuntu-release-upgrader:ubuntu/master

[Patrick Wu]

Just update the fix as requested. Righ now I tired to skip executing when it is using a non-root user
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https://code.launchpad.net/~callmepk/ubuntu-release-upgrader/+git/ubuntu-release-upgrader/+merge/384183
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