- Create multibranch pipeline project.
- Under project configuration, add GitHub source.
- Select "All branches get the same properties" under Property Strategy.
- Add "Suppress automatic SCM triggering" property.
- Save configuration.
- Make sure that GitHub repo configured at step 2 sends push notifications to your Jenkins instance via /github-webhook endpoint.
- Push something to the repo.
Build triggering was suppressed.
Build is triggered.
This got broken after recent 1.x -> 2.x updates to SCM API and Co.