class RSpec::Core::Configuration

def bisect_runner=(value)
  if @bisect_runner_class && value != @bisect_runner
    raise "`config.bisect_runner = #{value.inspect}` can no longer take " \
      "effect as the #{@bisect_runner.inspect} bisect runnner is already " \
      "in use. This config setting must be set in a file loaded by a " \
      "`--require` option (passed at the CLI or in a `.rspec` file) for " \
      "it to have any effect."
  end
  @bisect_runner = value
end