fix: allow cloned stream to be unref'd (nodejs#1700)

lib/fetch/body.js

@@ -261,13 +261,16 @@ function cloneBody (body) {
   // 1. Let « out1, out2 » be the result of teeing body’s stream.
   const [out1, out2] = body.stream.tee()
   const out2Clone = structuredClone(out2, { transfer: [out2] })
+  // This, for whatever reasons, unrefs out2Clone which allows
+  // the process to exit by itself.
+  const [, finalClone] = out2Clone.tee()
 
   // 2. Set body’s stream to out1.
   body.stream = out1
 
   // 3. Return a body whose stream is out2 and other members are copied from body.
   return {
-    stream: out2Clone,
+    stream: finalClone,
     length: body.length,
     source: body.source
   }

test/fetch/response.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const { test, teardown } = require('tap')
+const { test } = require('tap')
 const {
   Response
 } = require('../../')
@@ -248,6 +248,3 @@ test('constructing Response with third party FormData body', async (t) => {
   t.equal(contentType[0], 'multipart/form-data; boundary')
   t.ok((await res.text()).startsWith(`--${contentType[1]}`))
 })
-
-// This is needed due to https://github.com/nodejs/node/issues/44985
-teardown(() => process.exit(0))