message: Simplify, since that conditional gets executed in stan before the value is being passed
diff: @@ -7,8 +7,7 @@ def skipRemainingStages = false
  def setupCXX(CXX = env.CXX) {
  unstash 'CmdStanSetup'
  - stanc3_bin_url = params.stanc3_bin_url ?: "nightly"
  - stanc3_bin_url_str = stanc3_bin_url != "nightly" ? "\nSTANC3_TEST_BIN_URL=${stanc3_bin_url}\n" : ""
  + stanc3_bin_url_str = params.stanc3_bin_url != "nightly" ? "\nSTANC3_TEST_BIN_URL=${params.stanc3_bin_url}\n" : ""
  writeFile(file: "make/local", text: "CXX=${CXX} ${stanc3_bin_url_str}")
  }
  