"vue-cli-service build" does not use specified entry point when using "--target app"

[TAGC]

Version

3.0.0-beta.16

Reproduction link

TAGC/vue-expandable-grid@5928e09

Steps to reproduce

1. $ npm install
2. $ npm run build:demo

What is expected?

Given build:demo is defined as vue-cli-service build ... demo/src/main.ts, I expect vue-cli-service overrides the default Webpack entry point with ./demo/src/main.ts.

What is actually happening?

vue-cli-service ignores the specified entry point, using ./src/main.ts instead. This causes the following error to appear:

> vue-cli-service build --target app --name 'vue-infinite-grid' demo/src/main.ts


⠙  Building for production...Starting type checking and linting service...
Using 1 worker with 2048MB memory limit
⠼  Building for production...

Update package.json
 ERROR  Failed to compile with 1 errors                                                                                                                                      04:35:35

This relative module was not found:

* ./src/main.ts in multi ./src/main.ts
 ERROR  Build failed with errors.

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vue-cli-service serve respects the custom entry-point, and works correctly. vue-cli-service build also respects the entry-point when using --target lib or --target wc.

If I override the entry property for configureWebpack in vue.config.js, it uses this.