[Merge] ~gboutry/ubuntu/+source/python-os-traits:master into ~ubuntu-openstack-dev/ubuntu/+source/python-os-traits:master

[Nick Rosbrook]

Review: Approve

Okay, I saw that extend-diff-ignore= is already used here, so I extended it for .launchpad.yaml. Please ensure to do that on other PRs.

Merged and sponsored now.
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https://code.launchpad.net/~gboutry/ubuntu/+source/python-os-traits/+git/python-os-traits/+merge/488507
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