fix(ext/fetch): new Request should soft clone (#16869)

Previously the inner request object of the original and the new request
were the same, causing the requests to be entangled and mutable changes
to one to be visible to the other. This fixes that.

1 files changed, 7 insertions, 5 deletions

diff --git a/ext/fetch/23_request.js b/ext/fetch/23_request.js
index 508a29139..c09e3326f 100644
--- a/ext/fetch/23_request.js
+++ b/ext/fetch/23_request.js
@@ -157,14 +157,14 @@
    * @param {InnerRequest} request
    * @returns {InnerRequest}
    */
-  function cloneInnerRequest(request) {
+  function cloneInnerRequest(request, skipBody = false) {
     const headerList = ArrayPrototypeMap(
       request.headerList,
       (x) => [x[0], x[1]],
     );
 
     let body = null;
-    if (request.body !== null) {
+    if (request.body !== null && !skipBody) {
       body = request.body.clone();
     }
 
@@ -315,12 +315,14 @@
         if (!ObjectPrototypeIsPrototypeOf(RequestPrototype, input)) {
           throw new TypeError("Unreachable");
         }
-        request = input[_request];
+        const originalReq = input[_request];
+        // fold in of step 12 from below
+        request = cloneInnerRequest(originalReq, true);
+        request.redirectCount = 0; // reset to 0 - cloneInnerRequest copies the value
         signal = input[_signal];
       }
 
-      // 12.
-      // TODO(lucacasonato): create a copy of `request`
+      // 12. is folded into the else statement of step 6 above.
 
       // 22.
       if (init.redirect !== undefined) {