Emitting the restart policy as a `--restart` argument from a `docker-args-process-deploy` trigger exposed a latent gluing bug: proxy and builder triggers concatenated `$STDIN$output` with no separator, and the scheduler and builders appended `docker-args-process-*` output directly onto the older `docker-args-*` output, so adjacent arguments could merge into values like `--restart=on-failure:10--label`. A space is now inserted at both the trigger echo and the concatenation so arguments always stay separated.
Without this, it is possible to keep an old build image around in the case of failed builds, and due to missing label support, the image will never be cleaned up.
