Rshared volumes result in EOF error

Expected behavior

Working rshared mount flag.

Actual behavior

Unexpected API error.

Information

OS X: version 10.11.4 (build: 15E65)
Docker.app: version v1.11.0-beta6
Running diagnostic tests:
[OK]      docker-cli
[OK]      Moby booted
[OK]      driver.amd64-linux
[OK]      vmnetd
[OK]      osxfs
[OK]      db
[OK]      slirp
[OK]      menubar
[OK]      environment
[OK]      Docker
[OK]      VT-x
Docker logs are being collected into /tmp/20160407-135400.tar.gz.
Your unique id in bugsnag is: 7E223336-054C-4D69-950E-C807DE9DD5FC
Please quote this in all correspondence.

Steps to reproduce the behavior

> docker run --pid="host" --privileged="true" centos:7 nsenter --mount=/proc/1/ns/mnt -- mount --make-rshared /
> docker run --volume="/:/rootfs:rw" centos:7 /bin/true
> docker run --volume="/:/rootfs:rw,rshared" centos:7 /bin/true
docker: An error occurred trying to connect: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.23/containers/a2f5181ef548172d68ab5aa8fafe7e7b55bb787e50aa4f1a38ef6ea807a61d31/start: EOF.

Same commands work just fine agains 1.11-rc3 using Docker Machine

env FUSION_BOOT2DOCKER_URL=https://github.com/boot2docker/boot2docker/releases/download/v1.11.0-rc3/boot2docker.iso docker-machine create -d vmwarefusion test-rc3
docker-machine ssh test-rc3 docker run --pid="host" --privileged="true" centos:7 nsenter --mount=/proc/1/ns/mnt -- mount --make-rshared /
docker-machine ssh test-rc3 docker run --volume="/:/rootfs:rw,rshared" centos:7 /bin/true
docker-machine ssh test-rc3 docker run --pid="host" --privileged="true" centos:7 nsenter --mount=/proc/1/ns/mnt -- mount --make-rshared /