def _GetAllBuildersInConfig(trybot_config):
  """Returns a list of all variable builders referenced in config."""
  all_config_builders = set()
  for builders in trybot_config.itervalues():
    for builder in builders.itervalues():
      waterfall_builder = builder.get('waterfall_trybot')
      flake_builder = builder.get('flake_trybot')
      all_config_builders.add(waterfall_builder)
      all_config_builders.add(flake_builder)
  return list(all_config_builders)