moby: "error while getting pool information strconv.ParseUint: parsing "": invalid syntax" in docker info

I got an error while doing “docker info” with zfs backend driver. It shows “Zpool: error while getting pool information strconv.ParseUint: parsing “”: invalid syntax” on the page which seems to be an error or something is missing.

Version details: Host: Ubuntu 14.04.5 ZFS: 0.6.5.8-1~trusty Docker: Docker version 1.13.0, build 49bf474

root@atomic:/var/lib/docker# docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 1.13.0
Storage Driver: zfs
 Zpool: error while getting pool information strconv.ParseUint: parsing "": invalid syntax
 Zpool Health: not available
 Parent Dataset: tank/docker
 Space Used By Parent: 139264
 Space Available: 797687267328
 Parent Quota: no
 Compression: lz4
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins: 
 Volume: local
 Network: bridge host macvlan null overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 03e5862ec0d8d3b3f750e19fca3ee367e13c090e
runc version: 2f7393a47307a16f8cee44a37b262e8b81021e3e
init version: 949e6fa
Security Options:
 apparmor
Kernel Version: 3.13.0-107-generic
Operating System: Ubuntu 14.04.5 LTS
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 7.761 GiB
Name: atomic
ID: WSPC:FV5I:4AMK:5QB7:NHMU:43P3:5LAI:JBE7:SZIN:KT6H:DMDZ:R26T
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
WARNING: No swap limit support
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

I am not sure which command Docker uses, outputs of some ZFS commands for reference:

root@atomic:/var/lib/docker# zpool list
NAME   SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
tank  2,72T  1,91T   830G         -      -    70%  1.00x  ONLINE  -

root@atomic:/var/lib/docker# zfs list
NAME                    USED  AVAIL  REFER  MOUNTPOINT
tank                   1,91T   743G   144K  none
tank/burp               419G   743G   419G  /var/spool/burp
tank/data              1,49T   743G  1,49T  /var/disk
tank/docker             348K   743G   348K  /var/lib/docker
tank/lxc               2,37G   743G  2,37G  /var/lib/lxc
tank/lxc-abby          1,05G   743G  1,04G  /var/lib/lxc/abby
tank/mysql             42,1M   743G  42,1M  /var/lib/mysql
tank/postgresql        15,3M   743G  15,3M  /var/lib/postgresql
tank/squeezeboxserver   491M   743G   185M  /var/lib/squeezeboxserver
tank/twonky            2,88M   743G  2,88M  /var/lib/twonky
tank/www                869M   743G   858M  /var/www

root@atomic:/var/lib/docker# zpool status tank
  pool: tank
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
        still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(5) for details.
  scan: scrub repaired 0 in 6h9m with 0 errors on Sun Dec 27 21:07:45 2015
config:

        NAME                        STATE     READ WRITE CKSUM
        tank                        ONLINE       0     0     0
          mirror-0                  ONLINE       0     0     0
            wwn-0x50014ee20aeb2e08  ONLINE       0     0     0
            wwn-0x50014ee26040a451  ONLINE       0     0     0
        cache
          atomic--vg-zfsaarc        ONLINE       0     0     0

errors: No known data errors