Automatic merge from submit-queue (batch tested with PRs 55301, 55319, 54018, 55322, 55125). 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>.
Bump minimum supported go version to 1.9.1
**What this PR does / why we need it**:
If #55293 gets merged, we should bump minimum_go_version to 1.9.1
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
ref: #51375https://github.com/kubernetes/kubernetes/pull/55293#issuecomment-342723106
**Special notes for your reviewer**:
/cc @cblecker @ixdy @luxas
**Release note**:
```release-note
The minimum supported go version bumps to 1.9.1.
```
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