fix fetch 401 loop

lib/web/fetch/index.js

@@ -1675,6 +1675,11 @@ async function httpNetworkOrCacheFetch (
 
       // 4. Set the password given request’s current URL and password.
       // requestCurrentURL(request).password = TODO
+
+      // In browsers, the user will be prompted to enter a username/password before the request
+      // is re-sent. To prevent an infinite 401 loop, return a network error for now.
+      // https://github.com/nodejs/undici/pull/4756
+      return makeNetworkError()
     }
 
     // 4. Set response to the result of running HTTP-network-or-cache fetch given

test/fetch/401-statuscode-no-infinite-loop.js

@@ -0,0 +1,26 @@
+'use strict'
+
+const { fetch } = require('../..')
+const { createServer } = require('node:http')
+const { once } = require('node:events')
+const { test } = require('node:test')
+const assert = require('node:assert')
+
+const { closeServerAsPromise } = require('../utils/node-http')
+
+test('Receiving a 401 status code should not cause infinite retry loop', async (t) => {
+  let requestCount = 0
+
+  const server = createServer({ joinDuplicateHeaders: true }, (req, res) => {
+    requestCount++
+    console.log({ requestCount })
+    res.statusCode = 401
+    res.setHeader('WWW-Authenticate', 'Basic realm="test"')
+    res.end('Unauthorized')
+  }).listen(0)
+
+  t.after(closeServerAsPromise(server))
+  await once(server, 'listening')
+
+  await assert.rejects(() => fetch(`http://localhost:${server.address().port}`))
+})