Automatic merge from submit-queue
gcr.io/google_containers/mounttest: use Stat instead of Lstat
The current ``mt.go`` implementation use ``os.Lstat`` instead of ``os.Stat`` which does not read symlinks. Since implementation of ``AtomicWriter`` (which relies on existence of symlinks), the updated implementation of secret volume using the ``AtomicWriter`` can not be tested for secret file permission. Replacing ``Lstat`` with ``Stat`` allows to read symlinks and return permissions of target file. The change affects ``--file_perm`` and ``--file_mode`` options only.
``mounttest`` image is currently used by:
##### downwardapi_volume.go
- e2e: Downward API volume
- version: 0.6
- args: --file_content, --break_on_expected_content, --retry_time, --file_content_in_loop
##### empty_dir.go
- e2e: EmptyDir volumes
- version: 0.5
- args: --file_perm, --file_perm, ...
##### host_path.go
- e2e: hostPath
- version: 0.6
- args: --file_mode, ...
##### configmap.go
- e2e: ConfigMap
- version: 0.6
- args: --file_content, --break_on_expected_content, --retry_time, --file_content_in_loop
##### service_accounts.go
- e2e: ServiceAccounts
- version: 0.2
- args: --file_content
Some of the e2e tests use at least one of the affected options. Locally, I have updated all version of mounttest images to 0.7. All e2e tests pass with the new image.