cheets_CTS_N: Don't throw an error when all failures are waived.

When (passed=0, failed=waived>0) it should be regarded as success.

BUG=None
TEST=cheets_CTS_N.CtsSystemUiHostTestCases

Change-Id: I0192e5012280ae36c2289aa155e99e2d346fd0f9
Reviewed-on: https://chromium-review.googlesource.com/467187
Tested-by: Kazuhiro Inaba <kinaba@chromium.org>
Trybot-Ready: Kazuhiro Inaba <kinaba@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
(cherry picked from commit 19bfd2ef42eb77d0bd29ae1ac2b0203eb3110eb1)
Reviewed-on: https://chromium-review.googlesource.com/468494
Reviewed-by: Kazuhiro Inaba <kinaba@chromium.org>
diff --git a/server/site_tests/cheets_CTS_N/cheets_CTS_N.py b/server/site_tests/cheets_CTS_N/cheets_CTS_N.py
index f4744ea..141cf3c 100644
--- a/server/site_tests/cheets_CTS_N/cheets_CTS_N.py
+++ b/server/site_tests/cheets_CTS_N/cheets_CTS_N.py
@@ -418,7 +418,7 @@
             # The DUT has rebooted at this point and is in a clean state.
 
         # Final classification of test results.
-        if total_passed == 0 or failed > waived:
+        if total_passed + waived == 0 or failed > waived:
             raise error.TestFail(
                 'Failed: after %d retries giving up. '
                 'passed=%d, failed=%d, notexecuted=%d, waived=%d. %s' %