"nandroid"-style backup, error: Standard partitions were requested for backup, but not found in the partition map: boot, system, userdata

I have a LLD-L31 (`ieland`) with [TWRP 3.6.1_9-0 for `anne`](https://eu.dl.twrp.me/anne/) and `tetherback -0vv -N` returns:

```
tetherback v0.9.1
ADB: ('adb', '-d', 'version')
Found ADB version 1.0.41
Using default transfer method: adb exec-out pipe (--exec-out)
ADB: ('adb', '-d', 'shell', 'uname -r')
Device reports kernel 4.9.148
ADB: ('adb', '-d', 'shell', 'twrp -v')
Device reports TWRP version 3.6.1_9-0
ADB: ('adb', '-d', 'shell', 'cat /etc/fstab')
ADB: ('adb', '-d', 'shell', 'cd /sys/block; ls -d mmcblk*')
ADB: ('adb', '-d', 'shell', 'cat "/sys/block/mmcblk0/uevent"')
Reading partition map for mmcblk0 (0 partitions)...
partition map: 100%
ADB: ('adb', '-d', 'shell', 'cat "/sys/block/mmcblk0boot0/uevent"')
Reading partition map for mmcblk0boot0 (0 partitions)...
partition map: 100%
ADB: ('adb', '-d', 'shell', 'cat "/sys/block/mmcblk0boot1/uevent"')
Reading partition map for mmcblk0boot1 (0 partitions)...
partition map: 100%
ADB: ('adb', '-d', 'shell', 'cat "/sys/block/mmcblk0rpmb/uevent"')
Reading partition map for mmcblk0rpmb (0 partitions)...
partition map: 100%
ADB: ('adb', '-d', 'shell', 'cat "/sys/block/mmcblk1/uevent"')
Reading partition map for mmcblk1 (0 partitions)...
partition map: 100%

Partition map:

BLOCK DEVICE PARTITION NAME SIZE (KiB) MOUNT POINT FSTYPE
-------------- ---------------- ------------ ------------- --------
Total: 0

Backup plan:

PARTITION NAME FILENAME FORMAT
---------------- ---------------- -----------------
boot boot.emmc.gz gzipped raw image
system system.emmc.gz gzipped raw image
userdata userdata.emmc.gz gzipped raw image

usage: tetherback [-h] [--version] [-s DEVICE_ID] [-o OUTPUT_PATH] [-N] [-0] [-V] [-v] [-f] [-t | -x | -6 | -P] [-M] [-D] [-R] [-C] [-U] [-S] [-B] [-X NAME] [--extra-raw NAME]
tetherback: error: Standard partitions were requested for backup, but not found in the partition map: userdata, boot, system
Please report this issue at https://github.com/dlenski/tetherback/issues
Please post the entire output from tetherback!
```
I tried also without `-0`, but it encounters the same error.