Error POST if body is instance of Buffer

[zdm]

Bug Description

const res = await fetch( "https://api.github.com/repos/softvisio/playground", {
    "method": "PATCH",
    "body": Buffer.from( "test" ),
    "duplex": "half",
} );

returns error:

Cannot perform ArrayBuffer.prototype.slice on a detached ArrayBuffer

This worked previously.
Introduced in undici v7.19.2.

Reproducible By

Expected Behavior

Logs & Screenshots

Environment

undici: 7.19.2

Additional context

[zdm]

TypeError: fetch failed
    at d:\projects\corejslib\core\node_modules\undici\index.js:127:13
    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)
    at async fetch (file:///d:/projects/corejslib/core/lib/fetch.js:135:15)
    at async file:///D:/projects/devel/tmp/1.js:10:13 {
  [cause]: TypeError: Cannot perform ArrayBuffer.prototype.slice on a detached ArrayBuffer
      at ArrayBuffer.slice (<anonymous>)
      at extractBody (d:\projects\corejslib\core\node_modules\undici\lib\web\fetch\body.js:113:38)
      at safelyExtractBody (d:\projects\corejslib\core\node_modules\undici\lib\web\fetch\body.js:293:10)
      at httpNetworkOrCacheFetch (d:\projects\corejslib\core\node_modules\undici\lib\web\fetch\index.js:1657:22)
      at process.processTicksAndRejections (node:internal/process/task_queues:103:5)
      at async httpFetch (d:\projects\corejslib\core\node_modules\undici\lib\web\fetch\index.js:1142:33)
      at async mainFetch (d:\projects\corejslib\core\node_modules\undici\lib\web\fetch\index.js:596:20)
}

[zdm]

It calls extractBody method twice.
First time it converts Buffer to Uint8Array.
Second - it tries to make slice from Uint8Array. What for?

This should be fixed.