Before this change, a warning would be printed if the `~/.docker/config.json`
file was empty:
mkdir -p ~/.docker && touch ~/.docker/config.json
docker pull busybox
WARNING: Error loading config file: /root/.docker/config.json: EOF
Using default tag: latest
....
Given that we also accept an empty "JSON" file (`{}`), it should be
okay to ignore an empty file, as it's effectively a configuration file
with no custom options set.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>