vendors/execa.js/unload2
      unload = function unload2() {
        if (!loaded || !processOk(global.process)) {
          return;
        }
        loaded = false;
        signals.forEach(function(sig) {
          try {
            process4.removeListener(sig, sigListeners[sig]);
          } catch (er) {
          }
        });
        process4.emit = originalProcessEmit;
        process4.reallyExit = originalProcessReallyExit;
        emitter.count -= 1;
      };