Describe the bug

When trying to get SSR working, the sample project will not build in production mode. I think the code which sets process.env.NODE_ENV is being replaced, so that variable can't be assigned?

$ /Users/jakeginnivan/_code/vite-ts-ssr/vite-project/node_modules/.bin/vite build --outDir dist/server --ssr src/entry-server.ts
vite v2.5.6 building SSR bundle for production...
✓ 62 modules transformed.
[commonjs] Assigning to rvalue (33444:4) in /Users/jakeginnivan/_code/vite-ts-ssr/vite-project/node_modules/vite/dist/node/chunks/dep-9f74b403.js
file: /Users/jakeginnivan/_code/vite-ts-ssr/vite-project/node_modules/vite/dist/node/chunks/dep-9f74b403.js:33444:4
33442: 
33443:   if (!ctx.env) {
33444:     process.env.NODE_ENV = 'development';
           ^
33445:   }

My naive guess is that what is actually happening is 'production' = 'development'?

It is possible this is another variation of #3229, but thought I would open a fresh issue because the symptoms are a bit different.

Reproduction

https://github.com/JakeGinnivan/vite-ssr-build-issue

Then run yarn && yarn vite build --outDir dist/server --ssr src/entry-server.ts.

System Info

npx: installed 1 in 1.542s

  System:
    OS: macOS 11.5.2
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 258.38 MB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 14.17.3 - /usr/local/opt/node@14/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 6.14.13 - /usr/local/opt/node@14/bin/npm
  Browsers:
    Chrome: 93.0.4577.63
    Firefox: 91.0.2
    Safari: 14.1.2
  npmPackages:
    vite: ^2.5.4 => 2.5.6

Used Package Manager

yarn

Logs

--debug flag offered no additional info over the above error

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• 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 https://github.com/vuejs/vue-next instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.