Only use overlay driver in CI

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

script/ci

@@ -9,6 +9,7 @@
 set -e
 
 export DOCKER_VERSIONS=all
+export DOCKER_DAEMON_ARGS="--storage-driver=overlay"
 . script/test-versions
 
 >&2 echo "Building Linux binary"

script/test-versions

@@ -21,6 +21,7 @@ for version in $DOCKER_VERSIONS; do
     --volume="/var/lib/docker" \
     --volume="${COVERAGE_DIR:-$(pwd)/coverage-html}:/code/coverage-html" \
     -e "DOCKER_VERSION=$version" \
+    -e "DOCKER_DAEMON_ARGS" \
     --entrypoint="script/dind" \
     "$TAG" \
     script/wrapdocker nosetests --with-coverage --cover-branches --cover-package=compose --cover-erase --cover-html-dir=coverage-html --cover-html "$@"

script/wrapdocker

@@ -7,7 +7,9 @@ fi
 # If a pidfile is still around (for example after a container restart),
 # delete it so that docker can start.
 rm -rf /var/run/docker.pid
-docker -d --storage-driver="overlay" &>/var/log/docker.log &
+docker_command="docker -d $DOCKER_DAEMON_ARGS"
+>&2 echo "Starting Docker with: $docker_command"
+$docker_command &>/var/log/docker.log &
 docker_pid=$!
 
 >&2 echo "Waiting for Docker to start..."