Fix a bunch of pub tests that started running "pub get".

test/serve/404_page_test.dart

Index: test/serve/404_page_test.dart
diff --git a/test/serve/404_page_test.dart b/test/serve/404_page_test.dart
index fe5fcc9f07ab40e1b050314a7727e590de284097..3b478bcc837fe8fed1a6fa95e94f81c9aeea9c5b 100644
--- a/test/serve/404_page_test.dart
+++ b/test/serve/404_page_test.dart
@@ -18,7 +18,7 @@ main() {
   });
 
   integration("the 404 page describes the missing asset", () {
-    pubServe();
+    pubServe(shouldGetFirst: true);
 
     scheduleRequest("packages/foo/missing.txt").then((response) {
       expect(response.statusCode, equals(404));
@@ -32,7 +32,7 @@ main() {
   });
 
   integration("the 404 page describes the error", () {
-    pubServe();
+    pubServe(shouldGetFirst: true);
 
     scheduleRequest("packages").then((response) {
       expect(response.statusCode, equals(404));