Problem to share a container mount with host

[pwFoo]

Description

I try to share a container mount with the host like done with docker example mount in onboot section.

Steps to reproduce the issue:

Generated a custom mount image (alpine image)

onboot section

  - name: mount
    image: alpine:latest
    capabilities:
    - CAP_SYS_ADMIN
    binds:
    - /dev:/dev
    - /var:/var:rshared,rbind
    rootfsPropagation: shared
    command:
    - "/bin/mount"
    - "LABEL=<MY_LABEL>"
    - "/var/lib/docker"

Also tested with config by image label:

LABEL org.mobyproject.config='{"binds": ["/dev:/dev", "/var:/var:rshared,rbind", "/:/hostroot"], "capabilities": ["CAP_SYS_ADMIN"], "rootfsPropagation": "shared", "net": "new", "ipc": "new"}'

Same result

Describe the results you received:

Mount inside of the container, but isn't available in the host

/ # df
Filesystem           1K-blocks      Used Available Use% Mounted on

rbind is set twice

        {                          
            "destination": "/var",
            "type": "bind",  
            "source": "/var",
            "options": [ 
                "rshared",
                "rbind", 
                "rbind"      
            ] 
        },  

namespaces and rootfsPropagation:

    "linux": {                       
        "resources": {},             
        "namespaces": [              
            {                        
                "type": "pid"                                                  
            },
            {
                "type": "mount"   
            }                         
        ],                            
        "rootfsPropagation": "shared"
    }

Describe the results you expected:

Mount should be available in host root filesystem

How to fix it

Remove mount namespace lines from config.json and run with runc run again and it will work

            {
                "type": "mount"   
            } 

And it works fine

/ # df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1             10252256     36888   9674868   0% /var/lib/docker

Is it a bug or is something wrong with my yml file?
Is it possible to set mount namespace as needed in yml?

[pwFoo]

mount namespace is also set if I test docker.yml, but it works... Is there some magic in the linuxkit/init?