Merge branch 'master' into pedantic-syntax-cleanup

.gitlab-ci.yml

README.md

docs/upgrades.md

inventory/group_vars/all.yml

roles/kubernetes-apps/network_plugin/weave/tasks/main.yml

roles/kubernetes/preinstall/tasks/main.yml

roles/upgrade/post-upgrade/tasks/main.yml

roles/upgrade/pre-upgrade/tasks/main.yml

tests/templates/inventory-gce.j2

upgrade-cluster.yml