Running docker master on Windows

PS E:\> docker pull thisimagenamedoesnotexist
Using default tag: latest

Please login prior to pull:
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: EOF
PS E:\>

I think (pretty sure) this is coming from the backend, so I'm not sure I can fix it in docker/docker itself. Doing the same against a Linux daemon results in Error: image library/doesxnotxexist:latest not found, which is more what I'd expect.

@dmcgowan @aaronlehmann Is this by design by any chance in the current hub backend?