Fix comments disappearing in the "Comments" tab when clicking "Reply"

The "Comments" tab was changed to only show "saved" threads, which
works fine for newly created threads. But threads with unsaved replies
would also be considered "unsaved threads". That resulted in comments
disappearing when clicking "Reply".

Release-Notes: skip
Change-Id: Ibb9cf31e816276b506735eab5fea619e6d2ce589
diff --git a/polygerrit-ui/app/utils/comment-util_test.ts b/polygerrit-ui/app/utils/comment-util_test.ts
index ab21c67..7bf0c1e 100644
--- a/polygerrit-ui/app/utils/comment-util_test.ts
+++ b/polygerrit-ui/app/utils/comment-util_test.ts
@@ -16,6 +16,8 @@
   createUserFixSuggestion,
   PROVIDED_FIX_ID,
   getMentionedThreads,
+  isNewThread,
+  createNew,
 } from './comment-util';
 import {
   createAccountWithEmail,
@@ -72,6 +74,17 @@
     );
   });
 
+  test('isNewThread', () => {
+    let thread = createCommentThread([createComment()]);
+    assert.isFalse(isNewThread(thread));
+
+    thread = createCommentThread([createComment(), createNew()]);
+    assert.isFalse(isNewThread(thread));
+
+    thread = createCommentThread([createNew()]);
+    assert.isTrue(isNewThread(thread));
+  });
+
   suite('getPatchRangeForCommentUrl', () => {
     test('comment created with side=PARENT does not navigate to latest ps', () => {
       const comment = {