'ng update' does not work with yarn workspaces

先從 packages/angular/cli/commands/update-impl.ts 中約第 123 行連結的 update 命令實作開始，然後使用一個僅在 workspace-a/package.json 中包含 Angular 相依性的 Yarn workspace 重現該失敗。驗證從 workspace 目錄進行相依性解析時的行為；當 ng update 能夠找到並更新 workspace 的 Angular 相依性，且不要求它們存在於 root package.json 中時，即表示完成。

🐞 Bug report

Command (mark with an x)

- [ ] new
- [ ] build
- [ ] serve
- [ ] test
- [ ] e2e
- [ ] generate
- [ ] add
- [X] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc

Is this a regression?

No

Description

I am utilizing yarn workspaces -feature in my project. Problem is that I have to keep Angular & AngularCLI dependencies on root packages.json, otherwise 'ng update' command can't figure out the version I currently have. I'd rather keep root package.json clean and move Angular & CLI dependencies to project/package.json to keep things isolated.

Looking at the code, update command resolves dependencies from root package, even when command is executed on package folder. Would it be possible to change behavior in a way that update would first check package dependencies and the fall back to root if nothing is found?

🔬 Minimal Reproduction

• init yarn workspace project as follows: https://yarnpkg.com/lang/en/docs/workspaces/
• init angular app with cli and move dependencies from root package.json to workspace-a/package.json (example from previous step)
• wait until new angular version is available
• cd to 'workspace-a' and run 'ng update'. Command fails to find any dependencies to update.

🔥 Exception or Error

N/A

🌍 Your Environment

Angular CLI: 8.0.3
Node: 10.15.3
OS: win32 x64
Angular: 8.0.1
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router, service-worker

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.800.3
@angular-devkit/build-angular     0.800.3
@angular-devkit/build-optimizer   0.800.3
@angular-devkit/build-webpack     0.800.3
@angular-devkit/core              8.0.3
@angular-devkit/schematics        8.0.3
@angular/cli                      8.0.3
@angular/pwa                      0.800.3
@ngtools/webpack                  8.0.3
@schematics/angular               8.0.3
@schematics/update                0.800.3
rxjs                              6.4.0
typescript                        3.4.5
webpack                           4.30.0

Root package.json:

  "dependencies": {},
  "devDependencies": {
    "npm-run-all": "^4.1.5"
  },

'workspace-a/package.json':

"dependencies": {
    "@angular/animations": "~8.0.1",
    "@angular/common": "~8.0.1",
    "@angular/compiler": "~8.0.1",
    "@angular/core": "~8.0.1",
    "@angular/forms": "~8.0.1",
    "@angular/platform-browser": "~8.0.1",
    "@angular/platform-browser-dynamic": "~8.0.1",
    "@angular/pwa": "^0.800.3",
    "@angular/router": "~8.0.1",
    "@angular/service-worker": "~8.0.1",
    "@auth0/angular-jwt": "^2.1.0",
    "@ngx-translate/core": "^11.0.1",
    ...
    "rxjs": "~6.4.0",
    "tslib": "^1.9.0",
    "zone.js": "~0.9.1"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.800.0",
    "@angular/cli": "~8.0.3",
    "@angular/compiler-cli": "~8.0.1",
    "@angular/language-service": "~8.0.1",
    ...
  }

Anything else relevant?