This patch fixes exec to use the original (start-time) process exec
configuration. Otherwise, we were creating a brand new spec process w/o
additional groups for instance.
Spotted while integrating CRI-O with cri-test...The test was failing
with:
```
• Failure [10.640 seconds]
[k8s.io] Security Context
/home/amurdaca/go/src/github.com/kubernetes-incubator/cri-tools/pkg/framework/framework.go:72
bucket
/home/amurdaca/go/src/github.com/kubernetes-incubator/cri-tools/pkg/validate/security_context.go:407
runtime should support SupplementalGroups [It]
/home/amurdaca/go/src/github.com/kubernetes-incubator/cri-tools/pkg/validate/security_context.go:272
Expected
<[]string | len:1, cap:1>: ["0"]
to contain element matching
<string>: 1234
```
Signed-off-by: Antonio Murdaca <runcom@redhat.com>