Reland "Test luci.notifier."

This is a reland of 8df59bc74ebb4d0b8e5d80a8b4f5c674db2a9c4d

Relanding as is for testing.

Original change's description:
> Test luci.notifier.
>
> This CL will be reverted as soon as we verify that the fix applied in
> https://webrtc-review.googlesource.com/c/src/+/179062 works.
>
> Bug: None
> Change-Id: I1ef48f8e69d5592154b154de1700858aea4c32c4
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/179063
> Reviewed-by: Jeremy Leconte <jleconte@webrtc.org>
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#31703}

TBR=jleconte@webrtc.org

No-Try: True
Bug: None
Change-Id: Ib83eeb57d41f20cdfd54271f59d22f932e3b96b3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/179086
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31707}

tools_webrtc/autoroller/roll_deps.py

@@ -713,7 +713,8 @@ def main():
     logging.info('Uploading CL...')
     if not opts.dry_run:
       _UploadCL(commit_queue_mode)
-  return 0
+
+  raise Exception('Test')
 
 
 if __name__ == '__main__':