Wait longer in post-deployment test for the version to be updated. (d…

…art-lang#7617)

pkg/pub_integration/lib/script/publishing.dart

@@ -73,7 +73,15 @@ class PublishingScript {
       await dart.publish(_dummyDir.path,
           expectedOutputContains:
               'Successfully uploaded https://pub.dev/packages/_dummy_pkg version $_newDummyVersion');
-      await Future.delayed(Duration(seconds: 1));
+      // On appengine we may experiece a longer cache period for the public API.
+      // Waiting for up to 150 seconds for the version to be updated.
+      for (var i = 1; i <= 50; i++) {
+        await Future.delayed(Duration(seconds: 3));
+        final latest = await _pubHttpClient.getLatestVersionName('_dummy_pkg');
+        if (latest == _newDummyVersion) {
+          break;
+        }
+      }
       await _verifyDummyPkg();
 
       // upload the same version again