fix entires iteration for cookies (#346)

.changeset/tender-berries-hunt.md

@@ -0,0 +1,5 @@
+---
+'@edge-runtime/primitives': patch
+---
+
+fix entries iteration on Headers

packages/integration-tests/tests/headers.test.ts

@@ -10,3 +10,11 @@ test('sets header calling Headers constructor', async () => {
   headers.set('cookie', 'hello=world')
   expect(headers.get('cookie')).toBe('hello=world')
 })
+
+test('multiple headers', async () => {
+  const headers = new Headers()
+  headers.append('set-cookie', 'foo=chocochip')
+  headers.append('set-cookie', 'bar=chocochip')
+  expect(headers.get('set-cookie')).toBe('foo=chocochip, bar=chocochip')
+  expect([...headers]).toEqual([['set-cookie', 'foo=chocochip, bar=chocochip']])
+})

packages/primitives/src/primitives/fetch.js

@@ -27,8 +27,13 @@ class Request extends BaseRequest {
 
 const __entries = HeadersModule.Headers.prototype.entries
 HeadersModule.Headers.prototype.entries = function* () {
+  let sentSetCookie = false
   for (const [key, value] of __entries.call(this)) {
     if (key === 'set-cookie') {
+      if (sentSetCookie) {
+        continue
+      }
+      sentSetCookie = true
       const cookies = this.getSetCookie()
       yield [key, cookies.join(', ')]
     } else {