Automatic merge from submit-queue (batch tested with PRs 54045, 51375). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Upgrade to go1.9
**What this PR does / why we need it**:
Upgrade to go1.9. Upgrading is good. It's "the best golang release ever"!
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#49484
**Special notes for your reviewer**:
**Release note**:
```release-note
Upgrade to go1.9
```
/assign @luxas @ixdy @wojtek-t
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