Backup-resume on Ephemeral buckets fails if there has been a KV rollback during the prior backup that failed

Build : 5.0.0-3497

The test does the following :
1. 1-node cluster having an Ephemeral buckets loaded with some documents
2. Initiate a backup
3. While the backup is going on, kill beam.smp
4. Backup fails with the following error, which is expected :
Error backing up cluster: Not all data was backed up due to connectivity issues. Check to make sure there were no server side failures during backup. See backup logs for more details on what wasn't backed up.
5. Now re-run backup with resume flag.
6. Note, the Ephemeral bucket will have 0 documents.
7. Backup with resume flag now hangs infinitely.

cbbackupmgr log attached.