class RSpec::Core::Configuration

def deprecation_stream=(value)
  if @reporter && !value.equal?(@deprecation_stream)
    warn "RSpec's reporter has already been initialized with " \
      "#{deprecation_stream.inspect} as the deprecation stream, so your change to "\
      "`deprecation_stream` will be ignored. You should configure it earlier for " \
      "it to take effect, or use the `--deprecation-out` CLI option. " \
      "(Called from #{CallerFilter.first_non_rspec_line})"
  else
    @deprecation_stream = value
  end
end