Currently, we ignore errors that's returned for kill backup cursor command. So, shard merge can miss killing the backup cursor opened on the donor primary due to recipient primary shutdown or due to some transient n/w error. This would be bad, especially, when there is an orphaned active backup cursor on donor on shard merge abort. Currently, we only allow one active open backup cursor on a node at any point of time. This would shard merge retry or backup service to cause outage.