Automatic merge from submit-queue (batch tested with PRs 53694, 53919). 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>.

Do not crash when groupVersion doesn't have a group

**What this PR does / why we need it**: fixes a crash when the group is empty, because it assumes that split will return a two element array. Which it doesn't.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes kubernetes/kubectl#78

**Special notes for your reviewer**:

**Release note**:
```release-note
NONE
```