Release branches e2e's should use k8s from release branches

[pipejakob]

Is this a BUG REPORT or FEATURE REQUEST?

BUG REPORT (of e2e test)

Our kubeadm e2e test that runs against the release-1.6 branch currently specifies --kubernetes-version latest when initializing the cluster. This is probably the correct behavior for our tests against the master branch, but this should really be latest-1.6 for the release-1.6 job, which will require new plumbing to kubetest.

Relevant part of kubetest: https://github.com/kubernetes/test-infra/blob/ab9c9911b771807f179e4cbab80b883042f27ba4/kubetest/anywhere.go#L53

The 1.6 job on testgrid: https://k8s-testgrid.appspot.com/release-1.6-blocking#kubeadm-gce-1.6

[luxas]

@pipejakob This is fixed, right?

[timothysc]

@pipejakob ping.

[luxas]

@pipejakob ping

[pipejakob]

This will be fixed by kubernetes/test-infra#2761. The reviewer requested some changes that I haven't had time to address yet. It's definitely in my queue.

[luxas]

@pipejakob I updated the issue description to count both for v1.6 and v1.7

[pipejakob]

kubernetes/test-infra#2761 has been merged, and our release-1.6 and release-1.7 jobs are back to green:

https://k8s-testgrid.appspot.com/google-gce#gce-kubeadm-1.6
https://k8s-testgrid.appspot.com/google-gce#gce-kubeadm-1.7

[luxas]

Thank you a lot @pipejakob for fixing that!