only display 'Engine Version' when it's not empty

Signed-off-by: Victor Vieux <vieux@docker.com>

api/client/info.go

@@ -35,7 +35,7 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 
 	fmt.Fprintf(cli.out, "Containers: %d\n", info.Containers)
 	fmt.Fprintf(cli.out, "Images: %d\n", info.Images)
-	fmt.Fprintf(cli.out, "Engine Version: %s\n", info.ServerVersion)
+	ioutils.FprintfIfNotEmpty(cli.out, "Engine Version: %s\n", info.ServerVersion)
 	ioutils.FprintfIfNotEmpty(cli.out, "Storage Driver: %s\n", info.Driver)
 	if info.DriverStatus != nil {
 		for _, pair := range info.DriverStatus {