Automatic merge from submit-queue (batch tested with PRs 52109, 52235, 51809, 52161, 50080). 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>..
Allow kubectl cp large amounts of files from container
When we try to copy out a dir with large amounts of files from container, we hit such error:
```bash
kubectl cp mypod:/ ./a/
tar: Removing leading `/' from member names
tar: Removing leading `/' from hard link targets
error: open a/usr/share/zoneinfo/Asia/Rangoon: too many open files
```
This is because kubectl opens too many files at the same. We should close them after Write() function.
**Release note**:
```
NONE
```
it happens when copy directory to pod and the directory
path ends with '/'.
for example:
kubectl cp /XX/XX/ XX-POD:/XX/XX
modified: pkg/kubectl/cmd/cp.go
modified: pkg/kubectl/cmd/cp_test.go
* Rename variables and functions to match Go convention.
For example, UsageError --> UsageErrorf.
* Remove redundant or unreachable code.
* Simplify some utility functions (no functionality changes).
* Fix hanging 'if { return } else { return }' constructs.
* Fix several incorrect printf verbs.
Kubernetes Submit Queue