When Size was reverted to be equal to VirtualSize, the df command
formatter was not correctly updated to account for the change.
Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
How to test (it should not print `{}`, and just returns JSON with the actual data):
$ docker images --format '{{json .}}'
$ docker container stats --format '{{json .}}'
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>