[Bug?]: `explain peer-requirements` flags `peerDependencies` met by parent itself as missing

Self-service

• I'd be willing to implement a fix

Describe the bug

yarn explain peer-requirements complains about peerDependencies not being met when the parent is that dependency.

Related to https://github.com/yarnpkg/berry/issues/3382

To reproduce

Clone https://github.com/yarnpkg/berry/tree/b4b08736cb3a5612d765fe93b9624db374aeedf5 and run

$ yarn explain peer-requirements | grep webpack
[...]
p1a224 → webpack@npm:5.38.1 [e04a2] doesn't provide webpack to terser-webpack-plugin

$ yarn explain peer-requirements p1a224 
➤ YN0000: webpack@npm:5.38.1 [e04a2] doesn't provide webpack, breaking the following requirements:

➤ YN0000: terser-webpack-plugin@npm:5.1.3 [5eeea] → ^5.1.0 ✘

Environment

System:
  OS: Windows 10 10.0.19042
  CPU: (16) x64 AMD Ryzen 7 3700X 8-Core Processor
Binaries:
  Node: 16.8.0 - ~\AppData\Local\Temp\xfs-eac3ab51\node.CMD        
  Yarn: 3.1.0-rc.2.dev - ~\AppData\Local\Temp\xfs-eac3ab51\yarn.CMD
  npm: 7.21.1 - C:\nodejs\npm.CMD

Additional context

No response

Clone the referenced Yarn Berry commit and reproduce the report with yarn explain peer-requirements | grep webpack and yarn explain peer-requirements p1a224. Trace how peer requirements are evaluated and reported when the parent is the dependency itself. Done means this self-provided webpack requirement is no longer reported as missing, while the command still reports genuine unmet requirements.