Service Worker: FetchEvent.preventDefault() results in a network error

LayoutTests/http/tests/serviceworker/resources/fetch-event-network-error-worker.js

+// Test that multiple fetch handlers do not confuse the implementation.
+self.addEventListener('fetch', function(event) {});
+
+self.addEventListener('fetch', function(event) {
+    var testcase = new URL(event.request.url).search;
+    switch (testcase) {
+    case '?reject':
+      event.respondWith(Promise.reject());
+      break;
+    case '?prevent-default':
+      event.preventDefault();
+      break;
+    case '?prevent-default-and-respond-with':
+      event.preventDefault();
+      break;
+    }
+  });
+
+self.addEventListener('fetch', function(event) {});
+
+self.addEventListener('fetch', function(event) {
+    var testcase = new URL(event.request.url).search;
+    if (testcase == '?prevent-default-and-respond-with')
+      event.respondWith(new Response('responding!'));
+  });
+
+self.addEventListener('fetch', function(event) {});