Fix shared mount of /run

Needs util-linux for now, see https://github.com/docker/moby/issues/424

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/packages/docker/etc/init.d/docker

@@ -13,6 +13,9 @@ start()
 
 	pidfile="/run/docker.pid"
 
+	# mount /run shared eg for volume drivers
+	mount -o remount,bind,shared /run
+
 	# create cgroups mount for systemd containers
 	if [ ! -d /sys/fs/cgroup/systemd ]
 	then