在上游第一个地址出现404等错误时，可以自动切换到第二个地址 #394
Description
例行检查 / Checklist
- [ OK] 我已确认目前没有类似 issue (I have checked for similar issues)
- [ OK] 我已确认我已升级到最新版本 (I have updated to the latest version)
- [ OK] 我已完整查看过项目 README，已确定现有版本无法满足需求 (I have read the README and confirmed the current version does not meet my needs)
- [ OK] 我理解并愿意跟进此 issue，协助测试和提供反馈 (I am willing to follow up on this issue, assist with testing, and provide feedback)
- [ OK] 我理解并认可上述内容，并理解项目维护者精力有限，不遵循规则的 issue 可能会被无视或直接关闭 (I understand and agree to the above, and I understand that the maintainers have limited time, so issues that do not follow the rules may be ignored or closed directly)
功能描述 / Feature Description
在上游第一个地址出现404等错误时，可以自动切换到第二个地址
应用场景 / Use Case
兼容不用的上游地址，错误可以快速切换不影响
例如下面的第一个地址不支持文件上传，但是可以切换到第二个地址。404 没有自动切换
