Validate function is used to validate command options and should not get
any additional parameter. To preserve compatibility across all
kubectl commands, this PR removes all parameters in validate functions.
Kubernetes-commit: 8fb423bfabe0d53934cc94c154c7da2dc3ce1332
When trying to upload an unexisting file to a pod,
kubectl currently doesn't print any error message
and terminates with a zero exit code.
This adds a check and fails explicitly in such cases.
Kubernetes-commit: 3fa5b504423f169723b911547cd22ae85da168e0
inosato