refactoring; split tar-pipe command in two ready for first part to be handled by image-builder
refactoring; split tar-pipe command in two ready for first part to be handled by image-builder

cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless