[v3] build.lib overwrites build.rollupOptions.input

[aboutsimon]

Describe the bug

In v2, we are depending on a build configuration like so,

https://stackblitz.com/edit/vitejs-vite-gvrxpe?file=vite.config.js

to generate CSS files along our Web Components. I'm unable to reproduce this with vite v3 and i suspect, this is due to the fact, that build.lib overwrites build.rollupOptions.input and thus the two options cannot be combined anymore.

Is this the new intended behavior? Or am i missing something here?

Reproduction

https://stackblitz.com/edit/vitejs-vite-6y68ls?file=vite.config.js

System Info

System:
    OS: Linux 5.19 Arch Linux
    CPU: (4) x64 Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz
    Memory: 10.34 GB / 23.23 GB
    Container: Yes
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 16.15.1 - ~/.nvm/versions/node/v16.15.1/bin/node
    Yarn: 1.22.15 - ~/.nvm/versions/node/v16.15.1/bin/yarn
    npm: 8.11.0 - ~/.nvm/versions/node/v16.15.1/bin/npm
  Browsers:
    Chromium: 104.0.5112.79
    Firefox: 103.0.2
  npmPackages:
    vite: ^3.0.7 => 3.0.7

Used Package Manager

yarn

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
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• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

Duplicate of #9086.