Do not decode the body while we are following a redirect

lib/fetch/index.js

@@ -1942,6 +1942,7 @@ async function httpNetworkFetch (
           }
 
           let codings = []
+          let location = ''
 
           const headers = new Headers()
           for (let n = 0; n < headersList.length; n += 2) {
@@ -1950,6 +1951,8 @@ async function httpNetworkFetch (
 
             if (key.toLowerCase() === 'content-encoding') {
               codings = val.split(',').map((x) => x.trim())
+            } else if (key.toLowerCase() === 'location') {
+              location = val
             }
 
             headers.append(key, val)
@@ -1960,7 +1963,7 @@ async function httpNetworkFetch (
           const decoders = []
 
           // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding
-          if (request.method !== 'HEAD' && request.method !== 'CONNECT' && !nullBodyStatus.includes(status)) {
+          if (request.method !== 'HEAD' && request.method !== 'CONNECT' && !nullBodyStatus.includes(status) && !(request.redirect === 'follow' && location)) {
             for (const coding of codings) {
               if (/(x-)?gzip/.test(coding)) {
                 decoders.push(zlib.createGunzip())
@@ -1980,7 +1983,7 @@ async function httpNetworkFetch (
             statusText,
             headersList: headers[kHeadersList],
             body: decoders.length
-              ? pipeline(this.body, ...decoders, () => {})
+              ? pipeline(this.body, ...decoders, () => { })
               : this.body.on('error', () => {})
           })
 

test/fetch/client-fetch.js

@@ -10,6 +10,7 @@ const { fetch, Response, Request, FormData, File } = require('../..')
 const { Client, setGlobalDispatcher, Agent } = require('../..')
 const nodeFetch = require('../../index-fetch')
 const { once } = require('events')
+const { gzipSync } = require('zlib')
 
 setGlobalDispatcher(new Agent({
   keepAliveTimeout: 1,
@@ -440,3 +441,30 @@ test('fetching with Request object - issue #1527', async (t) => {
   await t.resolves(fetch(request))
   t.end()
 })
+
+test('do not decode redirect body', (t) => {
+  t.plan(3)
+
+  const obj = { asd: true }
+  const server = createServer((req, res) => {
+    if (req.url === '/resource') {
+      t.pass('we redirect')
+      res.statusCode = 301
+      res.setHeader('location', '/resource/')
+      // Some dumb http servers set the content-encoding gzip
+      // even if there is no response
+      res.setHeader('content-encoding', 'gzip')
+      res.end()
+      return
+    }
+    t.pass('actual response')
+    res.setHeader('content-encoding', 'gzip')
+    res.end(gzipSync(JSON.stringify(obj)))
+  })
+  t.teardown(server.close.bind(server))
+
+  server.listen(0, async () => {
+    const body = await fetch(`http://localhost:${server.address().port}/resource`)
+    t.strictSame(JSON.stringify(obj), await body.text())
+  })
+})