--- fixes: - If docker-puppet.py fails on any config_volume, it can be difficult to reproduce the failure given all the other entries in docker-puppet.json. Often to reproduce a single failure, one has to modify the json file, and remove all other entries, save the result to a new file, then pass that new file as $CONFIG. The ability to specify $CONFIG_VOLUME, which will cause docker-puppet.py to only run the configuration for the specified entry in docker-puppet.json whose config_volume value matches the user specified value has been added.