A Jenkins job with the Discover Pull Request feature enabled can fail to retrieve PR refs when it is configured to clone data from a Mirror.

According to Troubleshooting Smart Mirroring, under Pull request refs are not synchronized section, those refs are not automatically synced to the mirrors, causing the workflow to often fail.

This is a suggestion to handle this situation:

1. If the job is set to clone from the mirror, maybe the event needs to be sent from the mirror instead of the primary server.
2. If the event is sent from the primary server, the Jenkins plugin should have some kind of wait state until the mirror is ready.

Thanks!