error setting up bcache

[Marian Gasparovic]

Running command ['make-bcache', '-B', '/dev/sdc'] with allowed return codes [0] (capture=False)
        UUID: 86360f0e-6e94-4025-8a2d-4484df0f2f64
        Set UUID: ed6b5d1c-2ebb-4ebb-8578-176f3e22cb62
        version: 1
        block_size: 1
        data_offset: 16
        check just created bcache /dev/sdc if it is registered, try=1
        Running command ['udevadm', 'settle'] with allowed return codes [0] (capture=False)
        TIMED udevadm_settle(): 0.195
        Found bcache dev /dev/sdc at expected path /sys/class/block/sdc/bcache
        validating bcache backing device '/dev/sdc' from sys_path '/sys/class/block/sdc/bcache'
        bcache dev /dev/sdc at path /sys/class/block/sdc/bcache successfully registered on attempt 1/60
        devname '/dev/sdc' had holders: []
        Invalid number 0 of holding devices: "[]"
        An error occured handling 'bcache1': ValueError - Invalid number 0 of holding devices: "[]"
        finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: configuring bcache: bcache1
        TIMED BLOCK_META: 41.973
        finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: curtin command block-meta
        Traceback (most recent call last):
          File "/curtin/curtin/commands/main.py", line 202, in main
            ret = args.func(args)
          File "/curtin/curtin/log.py", line 97, in wrapper
            return log_time("TIMED %s: " % msg, func, *args, **kwargs)
          File "/curtin/curtin/log.py", line 79, in log_time
            return func(*args, **kwargs)
          File "/curtin/curtin/commands/block_meta.py", line 117, in block_meta
            return meta_custom(args)
          File "/curtin/curtin/commands/block_meta.py", line 2057, in meta_custom
            handler(command, storage_config_dict, command_handlers)
          File "/curtin/curtin/commands/block_meta.py", line 1778, in bcache_handler
            bcache_dev = bcache.create_backing_device(backing_device, cache_device,
          File "/curtin/curtin/block/bcache.py", line 489, in create_backing_device
            raise ValueError(err)
        ValueError: Invalid number 0 of holding devices: "[]"
        Invalid number 0 of holding devices: "[]"

Logs - https://oil-jenkins.canonical.com/artifacts/5d67fa9b-6d1d-47e2-a74b-82078860bc19/index.html

There's an old curtin bug that may, or may not, be related: bug 1750519