collection级别脚本修改url时，会清空hitchhiker.request

[y1376001532]

1. What went wrong (哪里出错)?
在Collection中，如果使用这种方式进行url参数的追加，会覆盖掉同Collection级别中的headers;
hitchhiker.setRequest({hitchhiker.request, url});

2. Steps to reproduce the problem (重现步骤):
Clear and concise reproduction instructions are important for us to be able to triage your issue in a timely manner (简洁清晰的重现步骤能够帮助我们更迅速地定位问题所在)

3. What is the expected behavior (期望表现)?
不应该覆盖hitchhiker.request, 只覆盖hitchhiker.request.url就好

4. Did this work before (之前是否正常)?
[Yes, No, N/A] [是，否，之前没用过]

5. Environment (环境):

• Hitchhiker Version (Hitchhiker版本): [e.g. V0.14]
• Use Docker or Installation Package (使用Docker还是安装包): [e.g. Docker/Installation Package]
• Node Version (If you use the installation package) (如果使用安装包的Node版本): [e.g. 8.11.3]
• Server OS (部署的系统): [e.g. Ubuntu, Windows, MacOS]
• Browser (浏览器): [e.g. Chrome, Firefox, Safari]

6. Additional Information (e.g. Screenshots, Links) (补充信息，截图，链接等)