variable number of builders in JJB

gistfile1.txt

- job-template:
    name: '{name}-spec'
    project-type: freestyle
    disabled: false
    description: variable number of builders example
    builders:
      - shell: !include-raw-escape scripts/setup.bash
      - '{custom-builders}'

- builder:
    name: builders-empty-list
    builders: ''

- builder:
    name: builder-bundler-1.5.2
    builders:
      - shell: "gem uninstall bundler"
      - shell: "gem install --version '~> 1.5.2' bundler"
      - shell: "echo 'a third step'"

- project:
    name: myproject-generic
    jobs:
      - '{name}-spec':
          custom-builders: builders-empty-list

- project:
    name: myproject-bundler-1.5.2
    custom-builders: builder-bundler-1.5.2
    jobs:
      - '{name}-spec'