vue-cli-service build --mode=production no longer works when used together with --watch

[wolthers]

Version

3.0.0-rc.3

Reproduction link

https://github.com/wolthers/vue-cli-bug

Steps to reproduce

Check out https://github.com/wolthers/vue-cli-bug

Run npm run watch in the project directory

What is expected?

Project should be recompiled on file changes in production mode

What is actually happening?

Project is recompiled in development mode

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There is no way to override mode if the build command is run and the watch flag is provided.

Bug was introduced in with any @vue/cli version after beta.16 in this commit: 3193b0d.