wx.cloud.downloadFile 下载文件问题

• 当前 Bug 的表现（可附上截图）

• 预期表现

在云开发控制台复制的fileID 不能使用wx.cloud.downloadFile  下载文件

错误信息:

<Error: errCode: -403003 internal server error: empty download url | errMsg: internal server error: empty download url>

console.error @ VM238:1

t.(anonymous function) @ WAService.js:1

(anonymous) @ WAService.js:1

a @ WAService.js:1

(anonymous) @ WAService.js:1

a @ WAService.js:1

t.invokeFailCompleteCallbacks @ WAService.js:1

(anonymous) @ WAService.js:1

Promise.catch (async)

(anonymous) @ WAService.js:1

(anonymous) @ WAService.js:1

exportAPI.(anonymou6

(anonymous) @ WASes function) @ WAService.js:1

onShow @ index.js:15rvice.js:1

__callPageLifeTime__ @ WAService.js:1

(anonymous) @ WAService.js:1

It @ WAService.js:1

(anonymous) @ WAService.js:1

(anonymous) @ WAService.js:1

i.emit @ WAService.js:1

emit @ WAService.js:1

(anonymous) @ WAService.js:1

(anonymous) @ WAService.js:1

n @ appservice?t=1562118605670:1673

(anonymous) @ appservice?t=1562118605670:1673

(anonymous) @ appservice?t=1562118605670:1673

_ws.onmessage @ appservice?t=1562118605670:1673

• 复现路径

cloud://bazi-99zet.6261-bazi-99zet-1259416447/ad.jpg 

• 提供一个最简复现 Demo