Previously if the Docker engine was not running the behaviour of
commands would vary depending on whether the --debug flag was provided.
For example, consider `docker logout`:
$ docker logout
Not logged in to
-- note the missing server URL
$ docker --debug logout
Warning: failed to get default registry endpoint from daemon (Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?). Using system default: https://index.docker.io/v1/
Not logged in to https://index.docker.io/v1/
-- note the server URL is present
This patch makes only the debug printing conditional on the `--debug` flag,
not the return value.
Signed-off-by: David Scott <dave.scott@docker.com>
a82e6868cc