Automatic merge from submit-queue
remove duplicate errors from aggregate error outputs
release-label-none
Duplicate error messages are sometimes shown when displaying aggregate errors:
`$ kubectl label pod/database-1-fn0r7 qwer1345%$$#=self`
```
* metadata.labels: Invalid value: "qwer1345%5602#": name part must match the regex ([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9] (e.g. 'MyName' or 'my.name' or '123-abc')
* metadata.labels: Invalid value: "qwer1345%5602#": name part must match the regex ([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9] (e.g. 'MyName' or 'my.name' or '123-abc')
* metadata.labels: Invalid value: "qwer1345%5602#": name part must match the regex ([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9] (e.g. 'MyName' or 'my.name' or '123-abc')
```
This patch removes any duplicate messages (adjacent or not) that appear in the final list of errors.