Exporting ZFS basejails includes basejail datasets

[gronke]

When exporting ZFS basejails (iocage-legacy), the automatically cloned basejail datasets get included in the export.

[-] ResourceBackup@my-zfs-basejail: ...
  [+] ExportConfig@my-zfs-basejail: OK [0.001s]
  [+] ExportFstab@my-zfs-basejail: OK [0.025s]
  [+] ExportRootDataset@my-zfs-basejail: OK [192.254s]
  [+] ExportOtherDatasets@my-zfs-basejail: OK [81.312s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr: OK [57.789s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/lib32: OK [2.392s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/share: OK [1.844s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/libdata: OK [0.277s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/libexec: OK [0.144s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/sbin: OK [0.604s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/src: OK [8.834s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/bin: OK [3.159s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/include: OK [1.982s]
    [+] ExportOtherDataset@my-zfs-basejail/root/usr/lib: OK [2.624s]
    [+] ExportOtherDataset@my-zfs-basejail/root/bin: OK [0.066s]
    [+] ExportOtherDataset@my-zfs-basejail/root/libexec: OK [0.054s]
    [+] ExportOtherDataset@my-zfs-basejail/root/data: OK [0.02s]
    [+] ExportOtherDataset@my-zfs-basejail/root/sbin: OK [0.13s]
    [+] ExportOtherDataset@my-zfs-basejail/root/lib: OK [0.166s]
    [+] ExportOtherDataset@my-zfs-basejail/root/boot: OK [0.976s]
    [+] ExportOtherDataset@my-zfs-basejail/root/rescue: OK [0.098s]
  [-] BundleBackup@my-zfs-basejail: ...

Expected behavior is that root and its child datasets are excluded from backups (because root is exported with rsync compare-dest instead).