OpenSearch/dev-tools/randomization.yml

randomization:
  elasticsearch:
    es150:
      version: 1.5.0
      branch: tags/v1.5.0
      lucene.version: 4.10.4
    es151:
      version: 1.5.1-SNAPSHOT
      branch: origin/1.5
      lucene.version: 4.10.4
    es160:
      version: 1.6.0-SNAPSHOT
      branch: origin/1.x
      lucene.version: 4.10.4