fetch: don't re-lowercase HeadersList (#3159)

tsctx · web-flow · commit e5b720041e97 · 2024-04-24T15:57:11.000+02:00
diff --git a/lib/web/fetch/request.js b/lib/web/fetch/request.js
@@ -459,8 +459,9 @@ class Request {
       // 4. If headers is a Headers object, then for each header in its header
       // list, append header’s name/header’s value to this’s headers.
       if (headers instanceof HeadersList) {
-        for (const [key, val] of headers) {
-          headersList.append(key, val)
+        for (const { 0: key, 1: val } of headers) {
+          // Note: The header names are already in lowercase.
+          headersList.append(key, val, true)
         }
         // Note: Copy the `set-cookie` meta-data.
         headersList.cookies = headers.cookies
