output from PACKER_LOG=1 packer validate ubuntu-13.10-en_US https://github.com/rstiller/packer-virtualbox/blob/master/ubuntu-13.10-en_US

output.txt

2013/11/16 22:59:49 Packer Version: 0.3.11  
2013/11/16 22:59:49 Packer Target OS/Arch: linux amd64
2013/11/16 22:59:49 Detected home directory from env var: /home/user
2013/11/16 22:59:49 Attempting to open config file: /home/user/.packerconfig
2013/11/16 22:59:49 File doesn't exist, but doesn't need to. Ignoring.
2013/11/16 22:59:49 Packer config: &{PluginMinPort:0 PluginMaxPort:0 Builders:map[amazon-ebs:packer-builder-amazon-ebs amazon-chroot:packer-builder-amazon-chroot amazon-instance:packer-builder-amazon-instance digitalocean:packer-builder-digitalocean openstack:packer-builder-openstack virtualbox:packer-builder-virtualbox vmware:packer-builder-vmware] Commands:map[build:packer-command-build fix:packer-command-fix inspect:packer-command-inspect validate:packer-command-validate] PostProcessors:map[vagrant:packer-post-processor-vagrant] Provisioners:map[ansible-local:packer-provisioner-ansible-local chef-solo:packer-provisioner-chef-solo file:packer-provisioner-file puppet-masterless:packer-provisioner-puppet-masterless shell:packer-provisioner-shell salt-masterless:packer-provisioner-salt-masterless]}
2013/11/16 22:59:49 Setting cache directory: /home/user/packer-virtualbox/packer_cache
2013/11/16 22:59:49 Environment.Cli: []string{"validate", "ubuntu-13.10-en_US"}
2013/11/16 22:59:49 command + args: []string{"validate", "ubuntu-13.10-en_US"}
2013/11/16 22:59:49 Loading command: validate
2013/11/16 22:59:49 Creating plugin client for path: /usr/bin/packer-command-validate
2013/11/16 22:59:49 Starting plugin: /usr/bin/packer-command-validate []string{"/usr/bin/packer-command-validate"}
2013/11/16 22:59:49 Waiting for RPC address for: /usr/bin/packer-command-validate
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Preparing to serve a command plugin...
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Plugin build against Packer ''
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Plugin minimum port: 10000
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Plugin maximum port: 25000
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Plugin address: 127.0.0.1:10000
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Waiting for connection...
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Serving a plugin connection...
2013/11/16 22:59:49 Executing command: validate
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Reading template: ubuntu-13.10-en_US
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Creating build: virtualbox
2013/11/16 22:59:49 Loading builder: virtualbox
2013/11/16 22:59:49 Creating plugin client for path: /usr/bin/packer-builder-virtualbox
2013/11/16 22:59:49 Starting plugin: /usr/bin/packer-builder-virtualbox []string{"/usr/bin/packer-builder-virtualbox"}
2013/11/16 22:59:49 Waiting for RPC address for: /usr/bin/packer-builder-virtualbox
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Preparing to serve a builder plugin...
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Plugin build against Packer ''
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Plugin minimum port: 10000
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Plugin maximum port: 25000
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Plugin address: 127.0.0.1:10002
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Waiting for connection...
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: 2013/11/16 22:59:49 Serving a plugin connection...
2013/11/16 22:59:49 Loading post-processor: vagrant
2013/11/16 22:59:49 Creating plugin client for path: /usr/bin/packer-post-processor-vagrant
2013/11/16 22:59:49 Starting plugin: /usr/bin/packer-post-processor-vagrant []string{"/usr/bin/packer-post-processor-vagrant"}
2013/11/16 22:59:49 Waiting for RPC address for: /usr/bin/packer-post-processor-vagrant
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Preparing to serve a post-processor plugin...
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Plugin build against Packer ''
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Plugin minimum port: 10000
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Plugin maximum port: 25000
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Plugin address: 127.0.0.1:10004
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Waiting for connection...
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: 2013/11/16 22:59:49 Serving a plugin connection...
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Preparing build: virtualbox
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 2013/11/16 22:59:49 Build 'virtualbox' prepare failure: 1 error(s) occurred:
2013/11/16 22:59:49 /usr/bin/packer-command-validate: 
2013/11/16 22:59:49 /usr/bin/packer-command-validate: * Output directory 'ubuntu-13.10-en_US' already exists. It must not exist.
Template validation failed. Errors are shown below.

2013/11/16 22:59:49 ui error: Template validation failed. Errors are shown below.
Errors validating build 'virtualbox'. 1 error(s) occurred:

* Output directory 'ubuntu-13.10-en_US' already exists. It must not exist.
2013/11/16 22:59:49 ui error: Errors validating build 'virtualbox'. 1 error(s) occurred:

* Output directory 'ubuntu-13.10-en_US' already exists. It must not exist.
2013/11/16 22:59:49 waiting for all plugin processes to complete...
2013/11/16 22:59:49 /usr/bin/packer-post-processor-vagrant: plugin process exited
2013/11/16 22:59:49 /usr/bin/packer-command-validate: plugin process exited
2013/11/16 22:59:49 /usr/bin/packer-builder-virtualbox: plugin process exited

renamed file to https://github.com/rstiller/packer-virtualbox/blob/master/ubuntu-13.10-x86_64-en_US/vm.json