Module identity is not preserved for symlinks when using the browser package.json field

[rtsao]

🐛 Bug Report

Jest fails to preserve module identity for symlinks when using the browser package.json field.

To Reproduce

Suppose we have the following dependency graph and these packages are installed via symlinks:

           ┌────────────────────┐
           │reproduction-example│
           └────────────────────┘
                      │
         ┌────────────┤
         │            │
         ▼            │
┌─────────────────┐   │
│has-browser-field│   │
└─────────────────┘   │
         │            │
         └────────────┤
                      │
                      ▼
            ┌──────────────────┐
            │needs-preserved-id│
            └──────────────────┘

Jest erroneously treats reproduction-example/needs-preserved-id and reproduction-example/has-browser-field/needs-preserved-id as distinct modules if has-browser-field specifies a browser field and the browser: true Jest config option is used.

If browser: false, then module identity is preserved as expected (#4761).

Expected behavior

Module identity should be preserved for symlinks when browser: true.

Link to repl or repo (highly encouraged)

Minimal repository: https://github.com/rtsao/jest-bug-repro-preserve-symlinked-module-ids

This reduced example demonstrates module identity being preserved correctly with browser: false but not with browser: true

envinfo

  System:
    OS: macOS Mojave 10.14.6
    CPU: (8) x64 Intel(R) Core(TM) i7-4850HQ CPU @ 2.30GHz
  Binaries:
    Node: 10.17.0 - ~/.nvm/versions/node/v10.17.0/bin/node
    Yarn: 1.19.2 - /usr/local/bin/yarn
    npm: 6.11.3 - ~/.nvm/versions/node/v10.17.0/bin/npm
  npmPackages:
    jest: ^25.1.0 => 25.1.0

[rtsao]

Found a duplicate issue: #7840

[github-actions]

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