File permission is incorrect in directory

Issue type: File permission
OS Version: Windows 10.0.14393 Build 14393
App version: Docker version 17.09.0-ce, build afdb6d4

Steps to reproduce:
1.Docker image is based on ubuntu:latest.
FROM ubuntu:latest
2.Run docker
docker run --rm -it -v %cd%:/workspace docker_build
3. Set umask to 0000
umask 0000
4. Create directory test in /workspace
mkdir test
5. Create file in test
touch test/test.txt
6. Delete test.txt in Windows
File Access Denied
You’ll need to provide administrator permission to delete this file
7. If create test.txt in /workspace, I can delete it in Windows.